I have a client with an old wood floor in front hall for whom I've designed a mosaic glass tile and river rock install. The quandry is in the install of different depths of glass and rock. Any suggestions on best method ... wet bed install may provide me with flexibility for depth variations. Pre arrangement/glue on mesh backing may not ... new ideas?

You're right.

If you wanted to do more of the work in the shop & attach it to mesh before going to the house, you could do that...........provided you don't put more than one depth on the same section of mesh. The practicallity of this will depend on the design.