I think sand is the most appealing to not only your eyes but also to your axolotls feet and your cleaning time. A turkey baster or siphon can simply be run over the topof the sand and it will pick up any mess.
To give you an idea, I put mine in a bucket and blasted it with a hose, then waited approximatly 5-10seconds and gentally poured out the water on top onto the garden. I did this about 25 times before it ran clear.
If you are starting from scratch on your tank put a plate on top of your sand which should not be more than 3-4cm deep (otherwise gas pockets can form),then pour the water over the plate. If you are just adding it to your tank and your filter has already been cycled make sure it is REALLY rinsed it as you don't want any particles wrecking your filter.
For my wide 3 foot tank I used approximatly 9kgs of childrens playsand.
Goodluck.
Blaze