We also have a 10' vanity and chose to do single pivot mirrors over each sink. We have a window between the sinks, so that made the decision easy for us. An 8' framed mirror is pretty big, and it may dominate the space more than a large unframed mirror would. Just something to consider.

If you're looking for "timeless" then I'd encourage you to go with two mirrors over one large expanse of glass.

With the taller ceilings, a tall mirror might look better, more proportional to the wall space.

And that leads to lighting. Over-mirror lighting can lead to facial shadows...I'd really encourage you to consider three sconces aside the mirrors versus the 4-light fixtures overhead of the mirrors.

The sconces would provide better and more flattering lighting for grooming and in my opinion would also be closer to your goal of being "timeless" versus the multi-bulb over-mirror fixtures.

I just went to Houzz dot com and after picking Photos/Bathroom I put in the search box 'two mirror vanity' and you will love all the examples you get if you try this. I print those I like and take them shopping with me so the store knows what I am talking about, or my contractor can see an example.

I love the two mirrors look. I copied these 2 inspiration pix from somewhere so you can see the diff. Your carpenter can frame out two mirrors or two medicine cabinets to match your vanity color. You can see the sconces as mongo recommended in that pic too. My med cab is Robern and the frame is also available from Robern. I ordered it unfinished and our contractor stained it to match the vanity.

Two mirror example

one mirror

My Robern cabinet and frame, stained with TimberSoy a no VOC soy based stain.

Our old bathrooms had huge mirrors that spanned the entire double sink vanities. When they were taken out during renovation, it was a HUGE difference and not necessarily in a positive way. The lighting in the room changed and they seemed much smaller.

We didn't replace either one. For the kids bath, we installed a tower between the sinks, tiled a 24inch backsplash and used 2 mirrors that I purchased at target. Meh. Not a fan of the cheap mirrors and the space seems smaller.

We have 2 large recessed medicine cabinets in the master.. no frame or beveled edge. Really love those and don't miss the large mirror because there's pretty glass mosaic instead.

With your large vanity, you could definitely use a large mirror and it would look great. The double mirrors do look nice in the pics above but IMO you would have to find some pretty large mirrors for a 10 foot vanity.

If you go to the mirrormate web site, you'll see how they frame out a large mirror to give presence over each of the sinks -- I like it!

My bath has a 90" vanity -- and we kept the large mirror. Its a large room (16' x 14') -- so 2 individual mirrors would have been too small an element in the room.

Thank you all so much for your advice...I still have not decided :o/ but I am going to check out the mirrormate website. I am slo hoping the trim carpenter has some good ideas. I had originally wanted 2 separate vanities, but when we sat down with the architect, it just didn't make sense to design it that way (and now I can't remember why!lol) Thanks again!

I think that both applications can be modern and stylish. If I had one long vanity, I would do one long and tall mirror that fills the entire space.