Tiles are much more desireable, and if you are confident in your tiling then why not go for it?
unless of course you actually are not
confident in your abilities tiling.
Why not look for a good "how-to" book on tiling to make sure you aren't missing anything vital and then go for it.
Remember that tile choice is important. Don't get smooth, glossy tiles for the floor, and I would avoid large tiles for wet floor areas. The smaller they are for wet areas that you walk on, the better. You will be much less likely to slip and break a hip ;-)
You can get different sizes for inside the shower area on the floor. Mosaic tiles are good and easy to work with sloping floors for drainage while providing good traction. You can use larger ones on the walls and the floor outside. Also, the chances of cracking smaller tiles is less if you are worried about that.
Outside of the shower you could have a combination large and small tile or however you want.
Some of the natural stone is nice because it is more porous and not is cold on the feet, just make sure whatever tile you choose is good for wet conditions while still providing traction and not feeling too "cold" on the footsies.
also, just noticed this thread, you may want to look at: Remodeling a walk-in shower