Best thing I've found is to drop whatever it is you want to place, leave the cell, then come back and let it reload. THEN pick up the item and put it where you want it. The game has a way of wanting to put "loose" items back wherever they were when you first dropped them but once the cell reloads with them in that spot one time it seems like you can move 'em without much hassle (as long as you don't take them back into your inventory).
Even so there are just some spots that are glitchy. I've got a bedside table that keeps trying to swallow half the stuff I sit on it. The stuff that doesn't taste good gets tossed over the side into the corner. So I just don't put anything on it.
Be advised though that if you have other NPCs in the house when you drop stuff, they may pick it up and give it back to you which defeats the purpose, or a fight may break out over who gets it. Supposedly it's only valuable items, but either that's incorrect or my housecarls really, really value wooden plates.
