I like the Chelsea round mirror from PB Teen, minus the flowers.

I don't think a white frames mirror would stand out from the wallpaper. Depending on the size of the mirror, I like the wisteria mirror because I think the frame looks like could be from that time period, I like the bento mirror because the color would go well with the wallpaper, and I like the faux-bois mirror for the same reson. But check out the french mirrors at Pierre Deux.

I like the frameless mirrors from Pottery Barn. I would pick the largest one. The wallpaper is a major statement, and a frameless mirror will reflect it and disappear, not causing a break.

I love the vintage style frameless mirrors. I would check ebay and antique stores for an authentic one with character.

I'd go frameless. The shapes are fun, and subtle enough not to clash with or detract from the wallpaper, which is busy enough on its own.

That said, the wisteria mirror is also lovely.

I think I would go with a white framed mirror for that bathroom, since the trim and the sink are white. The Wisteria mirror is lovely also.

I vote for the White framed mirror from C&B - most of the others would be a little too busy for that (georgeous) wall paper. The white one picks up the other white in the room and gives the eye a little rest.

I love the idea of a frameless mirror, but be careful, I considered those pottery barm mirrors myself but felt even the largest one was too small for my space.

If not, I like the idea of a white frame, but not just a rectangle, I prefer the bamboo one you pictured - something with a unique shape.

Thrift stores. Much, much more affordable and more ecletic selection.

I think that white and square or rectangular would go the best with the angular sink etc....

I sort of love that the mirror is small and minimal. A little bigger would be better.

Gothic Faux -Bois. So much money but perfect with the floral paper.

Be careful when ordering mirrors due to they may be larger or smaller than pictured. Measure carefully and do not go by the photo size on the web. See more wonderful mirror choices divided into categories: shaped, rectangular and square and round. http://www.TheDesignerInsider.com.

not white, you have enough white...I'd go for an ornate carved wood frame mirror painted in a groovy punchy color you pull from the paper. I'd go with a pink because it would complement what you have but still connect.

I've been looking at this mirror recently, I think it would look great in your space (painted)

http://newyork.craigslist.org/brk/fuo/2028236740.html

I love the frameless mirrors, the wisteria and the faux bois.

I also vote frameless. It would look perfect with your wallpaper.

I definitely would go for the frameless mirrors. They're more modern-looking than the framed ones, nod toward the overall aesthetic, but don't detract from your lovely wallpaper.

Here are some that might look nice:

http://www.decorpad.com/photo.htm?photoId=33201

I love sconces on either side of a bathroom mirror, maybe you can add a couple?

Ballard Designs has some nice decorative mirrors like this one:

http://www.ballarddesigns.com/abbey-mirror/mirrors/decorative-mirrors/14035

A green frame or a robin's egg blue might look good too:

http://thefrenchprovincialfurniture.com/painting-colorful-french-provincial-furniture/a-french-provincial-mirror-painted

I also love this look:

http://materialgirlsblog.com/losangeles/2009/08/26/wall-of-mirrors/

A single frameless mirror would look pretty. I really like these at Pottery Barn:

http://www.potterybarn.com/products/eleanor-frameless-mirrors/?pkey=cmirrors

This one is nice too:http://www.google.com/imgres?imgurl=http://media.onsugar.com/files/ons1/276/2765213/10_2009/b1b655d83768c4d9_neo_mirror.xxlarge.jpg&imgrefurl=http://www.maisonclassique.com/category/vendors&usg=__AdRexy2WMEpcOyJhiC38dLKzLh8=&h=500&w=500&sz=46&hl=en&start=23&sig2=7mztEIM4N-xdKcJEgO5Vfw&zoom=1&tbnid=nzFQuvamH7InnM:&tbnh=143&tbnw=144&ei=mlHLTIjHBYzmsQO3rcCGDg&prev=/images%3Fq%3Dvintage%2Bmirror%2Bdisplay%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26biw%3D1503%26bih%3D733%26tbs%3Disch:10%2C630&um=1&itbs=1&iact=rc&dur=440&oei=k1HLTMbDNo3QsAPBzIyZDg&esq=2&page=2&ndsp=35&ved=1t:429,r:7,s:23&tx=66&ty=81&biw=1503&bih=733

Nothing says "Tract House" like a frameless mirror in a bathroom...
...and white is just going to get lost in there.

I'd go for something with an interesting gilded frame:

http://www.horchow.com/store/catalog/prod.jhtml?itemId=cprod59140002&parentId=cat11350734&masterId=cat000092&index=26&cmCat=cat000000cat000089cat000092cat11350734
(Hang it vertically)

Or Bamboo:

http://www.horchow.com/store/catalog/prod.jhtml?itemId=cprod72500091&parentId=cat11570732&masterId=cat000092&index=17&cmCat=cat000000cat000089cat000092cat11570732

i'd go clean, simple, modern, so it doesn't compete with the wallpaper. love this mirror, though it might be too big:

http://www.ikea.com/us/en/catalog/products/40100521

One of the pretty frameless mirrors the author of the post listed as a possibility for the bathroom is never going to look "tract house", bepsf. Unless you know of nicer tract houses than I do.

I vote for 1, 8, or 9.

I like the the frameless mirrors too, although most of the PB mirrors look too small. I'd suggest using painter's tape to mock up your favorite options above the sink - then you'll have a chance to test out the scale before comitting without damaging the wallpaper.
I also like the pivot mirrors from RH. Some are frameless or have minimal metal rims. Very practical!
http://restorationhardware.com/catalog/category/products.jsp?link=OvalPivotMirrors&categoryId=cat1639028

I say white framed or one of the unusually shaped frameless ones. I love LGarcVA's idea of mocking up the mirror size, especially because I fear that some of these mirrors may still be too small.

Catrin here. THANK you all for these terrific suggestions. I am getting out my painter's tape tonight and then have some online shopping to do... So helpful....Thanks again.