Date: 6/8/2009 8:26 am EDT
Any type of base will work if it's thick enough to cover the perimeter space between the wall and tile.If you're installing tile base make sure the adhesive you use doen't fill the gap at the wall.
There is some debate if it's okay to install a vanity over a floating floor.Avaire tile unlike a laminate floor is a very stable product so if the vanity is not fastened to the floor with any adhesives and all the perimeter spaces are maintained you'll be fine. I've done it a number of time without any problems. Hope this helps.