We too have slept on Tempur Pedic mattress for years, and have one for our son too. Now looking for a good mattress for our daughter....and omg what info do I come accross...
Yes, the off gassing we noticed turns out to be a serious problem, not something that will go away after a few days (as the TP folks told us when we called to inquire about it). Is it dangerous? If you really want to know read the book "Toxic Bedrooms" available on Amazon.com
In our research we may have finally stumbled upon the culprit for our son's persistant ichy and dry skin, and possibly for a number of other health complications as well. Soon we'll know for sure. No, we'll not get a Tempur Pedic mattres for our daughter, nor any other "chemical" VOC emitting mattress for that matter.
We have received wonderful service from the folks at www.lifekind.com and we are planning to upgrade all of our beds to healthy organic mattrasses and pillows!!

I frequently put DWR beds into people's homes when designing, and as a result, they often purchase a Sonno mattress to go with them. I decided to try a mattress from valuememoryfoam.com for my own house when re-designing. I got the 12" mattress (still less then DWR's) and it is wonderful. since then, I have had a couple clients purchase mattresses from them, and everyone has been happy. If you're looking to save quite a bit of cash (money that can be spent elsewhere in your room- maybe a noguchi table for a sitting area in the corner) go for a mattress from there. You'll save and get a great bed! Hope that helps someone....
memory foam mattress

We purchased a sonno versa mattress after doing some research, unfortunately I kind of glazed by the comments re: off-gassing. Our sofa had a brief off-gassing period and it was manageable. However our experience with the sonno was far less benign. We could not sleep in the room for one week and had to keep the doors shut. It continued to off-gas appreciably for the full 30 days that they allow you to decide if you like it. I tried to convince myself that it really was not that bad but my eyes would be stinging after I lay down on it for a period of time. More concerning, over the entire 30 days that we had the mattress I had physical changes that usually I only have for a one week during the month. I did not make the connection to the mattress until finally, 30 days into the experience I googled "polyurethane toxic fumes" after waking up with a headache and generally feeling unhealthy. My search prior to buying the mattress led me to the wikipedia page on polyurethane which made it sound like a relatively benign material. The second search led me to the National Geographic Green Guide and they explained that polyurethane can off-gas toluene and phosgene both of which are neurotoxins. At this point I freaked out and we wrapped the mattress in plastic. It took about a week after for my body to change back to normal. Now I am reading, and people on this list have previously mentioned that these chemicals can mimic estrogen which completely makes sense based on what I was experiencing. If you are interested in a foam mattress, I would consider latex as it is natural, however, they do use chemicals to "fix" the latex. We decided to go back to good old spring technology and are stearing clear of polyurethane.

OK-I've done some research after reading the comments about off-gasing (I don't want to recommend anything bad to clients) I've had 4 people now put ThermoPlush mattresses in their homes (which cost a lot more than the mattresses I was having people get from ValueMemoryFoam) They are hands down the nicest mattresses I've put in anyone's home, but they are a little pricey. (a little extra $ is a small price to pay for a safer product though if you ask me...) If you have the money, try a ThermoPlush. They seem to be the way to go at this point.

Marge,
Thanks so much for the leeds! After reading the things above, we went for the thermoplush that you recommended. (I think we got a ultra - it was the thickest, softest one) WOW! perfect choice. You do sink pretty deep into it, but it feels great. It took us a few days to get used to the "hugged" feeling, but we just love it. My husband's back has never felt better. And it didn't smell at all when we got it (That's something else I read can be a problem) Plus, we went to store and tried a lot of memory foam mattresses, and none of them compare to this. It was a leap of faith (we ordered online because we couldn't find one locally) but I'm glad we went for it. Anyway, I'm going on and on-just wanted to say thanks!

I am having a tough time deciding between the DWR Sonno Mattresses, the Rest on Clouds Nimbus, and the Thermoplush. Can anyone point blank just tell me which one is the best? Any advice would be greatly appreciated!

I got a ThermoPlush Premium online. It's great. Shorter than the TempurPedic Deluxe for less money and a better feel. Just my 2 cents.

I'm sorry but those of you who love the Sonno are all out of your minds. I ordered this thing after all the ranting and raving here on AT. It doesn't merely "off gas for a day or two", it full on reeks like crazy formaldehyde and I couldn't stay in my apartment for days. It has been over 3 weeks and it still stinks up the whole place, and even after washing the sheets, they just absorb the odor. It feels like laying on the ground, in other words, it is HARD and there is no "sinking in" feeling. For $1500 it is not a good idea. I am returning it this week.

I got an even better one for you. My in-laws bought a foam mattress in Sept. The mom refused to sleep on it because it stank so bad and was giving her headaches. Her husband still slept on it for weeks, until she finally moved it to the garage. 6 months later, he was diagnosed with severe bulbous ALS! He CANNOT TALK OR WALK and now has a death sentence. In fact, he is now partialy demented. He is 72, and while I am not proposing that a mattress was the only cause, formaldehyde is a known cause of neurological disorders and an agent for leukemia, and a toxin shown in 2008 to increase risk of ALS 35%.

Maybe a mattress kicked him over the edge. Maybe it was just straight-up defective poison. All sorts of 'effects' are turning up. We live in a world where noone protects the average consumer. His wife called in to complain that the mattress still stank, and they offered a new one, saying that shipment had been 'bad'. Memory foam stinks to high heaven, folks. Call me nuts, but this is all TRUE, and if you want to spend a third of your life on a bed of toxins, be my guest, i know I wont be.

I just bought one and I am returning it....going back to my traditional Sealy Beutyrest. Thank god I kept it.