I love tile.
It's pretty, cheap and easy to clean.
I use slate tile in my enclosures. They're cut to fit the tank, but I didn't grout them inplace. I wanted to be able to remove them both for cleaning purposes and also for if we have to move the unit, it'll be really heavy if the tile is installed.
I wouldn't reccomend grouting the tiles in place, mostly because it would be hard to get poop off of them.
If you want to have the floor permanant, you may be able to silicone the cracks, and then use a non toxic sealant over the silicone.
I would reccomend just have the tiles sit in there. If you measure and cut them properly, then they won't have large gaps for toes to get stuck in. Mine are nice and tightly fit together, and when I take them out to clean them, I just wedge a butter knife between two tiles and pull one up. Once the first one is pulled up, they come out nice and easy. Looks just as nice, if not nicer than having them grouted in, and gives you more options.
You can always change the tiles up to if you get bored of them, or they chip, etc.
Ah, and yes they do have traction. Don't buy porcelyn or marble type tile, those are very slippery and may get too hot. Slate tiles absorb heat but don't reflect it, so they get warm but never hot. Glass type tiles will get hot enough to burn them.
There's hundreds of types of slate tile. I went to my local Re-Store and ended up with enough tile for 3 4X2 enclosures for under 10 bucks. All different types of slate.
I'd also reccomend (from personal experience) staying away from the layered types of slate. Those start to chip off when they become moist. (I soak mine in water/vinegar) for disinfecting, so after 6 months or so they weren't nearly as pretty, though they still work.
Pick a tile that feels somewhat rough when you drag your fingernail across it.
It also helps keep their nails filed down.