Oh what a wonderful wall - empty canvas. Re the painting b/f the mosaic, I advise against it. I painted my Lady of Guadalupe Shrine b/f I put a few pieces of mosaic on, and some of them have come off. Remember you'd be mosaicing onto paint, which tends to come off/chip. My suggestion is to mosaic right onto the wall, then paint what's left. It w/be beautiful from your description. I wouldn't worry about the different textures/thickness of the tess - the different levels w/create interest, even though it's a nightmare to grout. Let your imagination run wild, and be sure and show us WIP pictures.

Wonderful empty canvas, as you say, Slow. Wow, I would love to have a similar wall just waiting for mosaic to happen to it. I would mosaic the top and down to that line a la Gaudi, the only straight line of tiles would be the lower edge. I would indulge myself with curved, bulky pieces for the top, (half bowls, half cups, etc.). Then I would paint the rest of the wall either pale blue or terra cotta. It's going to be beautiful. I would use thinset for the adhesive and perhaps Rustoleum paint for the lower portion of the wall. Please please post pics as you go!

Good advice, SILVA. I forgot to say use thinset. Oh, BTW - I w/also put some kind of hanging water feature on the wall and do a real fantastic mosaic surrounding it. Google for ideas on wall water features. Here are some ideas.
water feature
water feature
and one of my favs
water feature

Wonderful idea. Especially love that last link . . .

Well, we've been in the house about 2 1/2 months now. Had major works done inside and are now tackling the outside (we are now into Spring here)
We painted the wall and I have decided to just mosaic the top otherwise way,way too much work!
So here is a preview.
I have absolutely no idea how long this will take as I can only do it when this area is shaded. Today when I started my tile glue was drying on the knife before I could even get it on the tile!
So early morning.
And then later evening with glass of wine in hand (should be interesting lol)

The Beginning............

I do not know how this will end up.

No preplanned design.
And no idea.

Oh well it will be fun anyway :)

And THAT's what matters. If you like it and enjoying doing it, what else matters. W/be an interesting project to watch. Love the blue paint.

Oh it looks like it is going to be so fun!!!

You are off to a great start!

Yes looks like a great beginning!!!

Keep us posted! Love the blue paint.