Well, I asked for a reality check - and you delivered! Most of you agreed that the Pottery Barn shell mirror was a little over the top, but that in the right location, it might just look okay (I think the key is toning down the mirror with neutrals so that it blends into its surroundings)...
Simple - Beachy - Spa-like
I'm sure that the mirror would look great in this room!
(Click here for the horizontal stripe tutorial)
I ended up following the advice of several commenters and have begun working on a miniature version; I am "shell-ifying" a small magnetic frame that has been unadorned and waiting for just the right makeover. I stuck with white shells, but there is still a lot of variation in color. I plan to cover it with a coat of glossy white paint to create a more simplistic look.
But, I will admit, I hadn't really considered the time involved...
This is a 4x6 frame. And I'm still not done. I'm beginning to think that the $600 that PB is charging is justified.
Thanks again for all of your input - you guys talked me down from that ledge - that crazy-shell-lady ledge.