HI -- Nice big bathroom ---- A colorful large painting would look nice or six framed pictures suitable for the moisture or a wallpaper mural. Or something sculptural .

Sculpture!! Make a statement!!!

Ooh, I would do a pique assiette mosaic ala Gaudi.
http://www.writedesignonline.com/Prompts/Gaudi-Wall.jpg

mural? mosaic? how about a nice big TV!

There are nice vent-less "fireplaces" that would mount on the wall and stick out about 4". All that is required is a small gas line. They have an igniter similar to what is on a gas outdoor cooker, so no electrical problems. They have a glass front and besides looking really nice they give off a bit of heat.

Something like this...

A group of botanical prints or lake view scenes.

I've a framed poster of 1890 soap ad with a cute toddler over my bathtub. It is an ad for Pear Soap. I had just attended school with a girl from that family and the resemblance was striking.

How about some built-in towel storage? Pretty and practical.

The problem is it's an exterior wall. Can't really build into it.

Same idea, only wall mounted shelving customized to your horizontal space.

Thanks for your ideas! I like the driftwood idea and will start searching :)

Since you have a granite "backsplash" of sorts I'd do a really fun wallpaper and one simple art piece or print on top.

Of course if this area is exposed to shower moisture make sure to use a heavy duty vinyl (commercial grade) paper...

HI -- I don't think a TV or a fireplace over the tub is a good idea at all - SAFETY FACTOR ( building codes ?) --- I love the driftwood sculpture idea ! - on a black background !!

You're right about a TV being a safety and code problem, but not the fireplace I mentioned which doesn't take power, only gas.

Have you considered a wall of candles? Perhaps even the battery ones if lighting them is too big a chore.....They would be especially relaxing backed with mirror.
Another idea is extending the mirror all the way across which would unify the room and reflect light since you cannot have a light over the tub. Perhaps a row of smaller framed mirrors hung over the installed mirror for interest....

here are a few more examples of walls of candles...

I like the candle idea, too! If you could combine the the two - a driftwood candle sculpture - it would be so beautiful. And on an off black matte background? Amazing!

I bet you could find a local artist in your lakeside community to commission a piece for you.

You have all been quite helpful. I didn't extend the mirror or consider a mirror treatment because the shower faces that wall and I don't want to look at that (!) The candle/driftwood sculpture sounds like a winner. Thanks!

Aha, understood! You can order antiqued mirror or smoked or veined if you want reflected light but not a true reflection of the shower.....I mention that because reflected candlelight is truly special. I think you will be happy with the candle driftwood sculpture. It is so in keeping with the location of the home. Enjoy!

ps you can even have mirror etched.....perhaps waves on sand behind the driftwood candle sculpture? if that is too high consider plain mirror topped with glass you etch yourself with a spray etching kit....very easy to use...can even do with blue tinted glass or mirror...then you would have the beach complete with the driftwood. :)