My 2 sen: David, depending on how humid your windowsill is, you can go for phals, as suggested by atmccmn, but they require high humidity but perfect drainage. Or you could go for minicattleyas (epicattleyas, ottaras or potinaras) which can tolerate drier conditions. Cattleyas are suitable if your window receives a bit of direct sunlight. I see neps hanging from the ceiling, which means light levels should be ok.. most importantly, bear in mind that orchids are NOT like CPs. while CPs don't mind being potted in moist sphagnum all the time, orchids like phals potted in sphagnum must be watered only when the top layer of sphag becomes dry. Keeping them wet continuously will result in root rot and eventual death of the plant. It is better to repot all new orchids in charcoal and water more frequently to be on the safe side. Good luck.
