Hi..my set-up actually incorporates both techniques. I have four pebble trays which cover my growing table. (easier to lift then one or two big ones) On each tray I have baker's cooling racks held up by small pieces of wood so the racks are about half an inch above the pebbles. The plants are on these racks....that way the bottoms of the pots are never touching the wet pebbles.
All my moss pots are four inchs...I have been looking and looking but haven't found any smaller size clay pots around here.
All my small ones that I already own have orchids in them.
Above one of the trays I have a wire rack (closet organizer, comes in various sizes with legs already on them) On this rack I have my smaller plants that need to be closer to the lights and below them are the shade lovers. The upper plants are spaced enough to let "dappled" light through. I also have my one mounted orchid hanging from the upper rack. There are four flourscent bulbs (four footers) above the whole thing and a CFL clamped at one end for the mini catts.
The whole set up is in the basement and I've been able to keep the humidity around 50% at plant level and 40% two feet above the table. Still trying to reach 60% without plastic drapes or a humidifier. Oh and constant, gentle arir circulation from above.
Hope this helps.
Judy