Around the World with Mouk -- it's my kid's favorite 'look book' lately. Tons to see, stickers to reposition, comments to read, and a funny little story line too.
http://www.amazon.com/Around-World-Mouk-Marc-Boutavant/dp/0811869261

I loved "Who Needs Donuts" by Mark Alan Stamaty when I was a kid; the story may be a little mature for your son but the illustrations will keep the whole family busy: http://www.amazon.com/Needs-Donuts-Mark-Alan-Stamaty/dp/0375825509/ref=sr_1_2?ie=UTF8&s=books&qid=1296757405&sr=1-2

And also by Richard Scarry: "What Do People Do All Day" and "Busy Busy Town" will keep little ones occupied.

Goodnight Gorilla and 10 Minutes to Bedtime by Peggy Rathmann
Snowmen at Night by Caralyn Beuhner
Gigi and Zachary's Around the World Adventure and Gigi and Zachary Go to Work by Gilles Eduar
The Mitten by Jan Brett

Any of the Eye Spy books. They're cheesy, but kids love them.

"Adele and Simon" by Barbara McClintock and it's sequel "Adele and Simon in America". Not quite as busy as Scarry but the illustrations are so utterly charming, you won't miss the extra visuals

My kids love this one; Imagine by Alison Lester.

Also for the granola set there's Gerda Mullers season books.

"A House is a House for Me" by Mary Ann Hoberman is AMAZING. Gorgeous illustrations and endless detail.

My 20 month old's current favorite is The Cat in the Hat Beginner Book Dictionary. It seems we can flip through it over and over again and like you said--it remains fresh because there are so many things to see. I've flipped through it about 2-3 times a day with him in the past week and so far he isn't tired of it yet....

We like the Look Alike books. They might be a bit mature for your 2 year old, but you find something new every time you look at them. My son also spends a lot of time looking at the pictures in the Life-Size Aquarium book. There are two Life-Size Zoo books as well.

We like Ispy around our house... there are some for older kids, but there also Ispy board books and some of the beginning readers. Also, any type of beginning dictionary.

If you are looking for more of a story book, one of the most popular at our house is Arnie the Donut. I warn you, you'll want a donut afterward or a donut pet :)

Any of the "Look & Find" books by Publishers International. We have several, most around $8. Yes, they are mostly character based, but they never fail to entertain for hours of long car rides.

For more literary, story driven books, check out Jan Brett. Her illustrations are lovely and intricate and fascinating. They tell complete stories of their own.

Animalia is another good one. There are a few other books by the same author that are similar and equally detailed.
I second Good Night Gorilla, 10 Minutes to Bedtime and all of the other Richard Scarry Books. We have them all and they are good for hours of entertainment.

Usborne have great find 1000 things in the city, country, on a farm, under the sea... books. And their puzzle books are full of the most fabulous details. My kids love them long before they can read... the pictures are so so so so so engaging!!!

Maybe these are a little bit old for you little one but my son has enjoyed Peter Spier books since he was in his early 3s. Many are wordless - like Noah's Ark - and some have a few words. One I really don't like to read because it is all sounds is Crash Bang Boom but DS loves it.

not sure about story line, but my toddler has richard scarry's biggest word book ever and big bird's big book. she loves them! they are huge, a little over two feet tall and just over 3 feet wide when open. when I ordered them I figured that they would just be blown up versions of regular books. they aren't--they are incredibly detailed pictures for kids to study.

they are a little expensive (about 25 for the scarry one and 35 for the big bird one from amazon). I lucked out and got them from gilt for about half that, but if something happened to them I would pay that much to replace them. they really are worth it.

http://www.amazon.com/Richard-Scarrys-Biggest-Word-Book/dp/0394873742/ref=sr_1_1?ie=UTF8&s=books&qid=1296773715&sr=1-1

http://www.amazon.com/Big-Birds-Book-Sesame-Street/dp/0394891287/ref=bxgy_cc_b_img_a

Somebody beat me to it - Who Needs Donuts by Mark Alan Stamaty is crazy busy. The story itself - is - er - interesting, but by the end of the book you think the artist is either a genius or completely insane. We read it to our 2-year-old and he loves discovering all the little details.

I second Animalia by Graeme Base - I read it when I was a kid and now that I am an adult, I really appreciate all that is hidden in the pictures.

Richard Scarry's Best? Story Book Ever. Both of my little boys have been crazy about it. It includes some of his stories published separately, but also pages about the seasons, vehicles, animals, poems for every month of the year. And all those awesome Scarry illustrations. They have never tired of it. http://www.amazon.com/Richard-Scarrys-Storybook-Little-Golden/dp/0307165485/ref=sr_1_4?s=books&ie=UTF8&qid=1296779147&sr=1-4.

Also, they love the Walter Wick I Spy books. Love.

my 25 month old has been a fan of I Spy books for a few months. When we first started, we just talked about all things on the page or I'd ask her if she can find a *blank* on the page. Now she actually does a pretty good job of finding the object shown on the preceding page.

We love 'Around the World with Mouk' too. Colourful, detailed and fun. My 2 and 5 year old both enjoy it.

I'll third Animalia - in fact, I was just reading it to my three month old today ;). The Eleventh Hour is also great. Graeme Base is an amazing illustrator and there really is a lot to see in his books. I'll second a House is a House for Me. Also like The Day Jimmy's Boa Ate the Wash. My two year old also loves looking at a "My First Dictionary" book. Can't say I'm a fan but there are plenty of objects to name!

We are Richard Scarry fans too. My son's absolute favorite is "What Do People Do All Day"

I'm so happy that you enjoy Rotraut Susanne Berner! We love her books in our house, and I find that she deserves to be better-known than she is.

In addition to the books that you have (we have the season by season editions), there are little board books which provide the backstory of some of the characters in the books -- the cats, the little girl who skates, the man with the goose, etc. They are available in French and German, and you can find them on amazon.fr and amazon.de.

She also produced a wonderful book called The Winter Book. It has poems and stories, so not quite what you are looking for, but she does build in some of the same sort of threads as in the other book with which you are familiar. In any case, it is a lovely complement to what you already have.

The books you are looking for are a type called "wimmelbuch", and are very popular in Germany. Just search under that term on amazon.de under "buchs", and you will see many other books along those same lines. There was a particularly gorgeous one I saw last year which was most impressive for the drawing quality and size -- almost 3 feet high! (will try to find the title).

Apart from this, my children are absolutely fascinated with the DK 24 HOURS series, which sadly is out of print. You can still find inexpensive copies of most of the books though. The conceit is that they tell the story of what happens in a specific location during a typical day -- what all the animals, birds and insects are doing at dawn, midmorning, afternoon, at dusk, and at night. It is fascinating, and although there is lots of explanatory text, there are lots of wonderful photos. It says it is for older children, but mine loved looking at the pictures when they were young.

Good luck and have fun!

"Anno's Journey" by Mitsumasa Anno is a beautifully illustrated wordless book--you follow a character through intricate illustrations of European villages (kind of like Where's Waldo, but less difficult, it can be a challenge to find where he is on each page). My 3 yr. old loves this book. There all these references in the illustrations to art and literature that are entertaining for us adults, too.

I Spy and Richard Scarry's Biggest Best First Book Ever (or whatever it's called!) are huge with my 20 mo old.

Oh! And "Harry the Dirty Dog"!!!

Where's the Cake? And Where's the Cake Now? by T. T. Khing. It's funny that they books says "translated from the Dutch" when they both don't any words in them. Great pictures, many different visual story lines. We enjoy making up new stories each time we "read" them.

Both of the books Manners and Feelings by Aliki are great for all the little details http://www.amazon.com/Manners-Aliki/dp/0688045790/ref=sr_1_2?s=books&ie=UTF8&qid=1296923443&sr=1-2