I like doing socks on 2 circs or magic loop...both on my KnitPick Options. I like doing them on Addis too. And absolutey positutely I do them toe-up and two at a time! (I like how the toes turn out toe-up better than top-down).
As far as patterns...I haven't really branched out into anything fancy yet. I just do a straightforward stockinette toe and foot, M1 increases for the gusset, and short row heel turn, and the "sl1 k1, ssk/p2tog p" heel flap.
Then I just do stockinette round and round til I get bored, and about two inches of k2p1 ribbing at the top. Voila! Just bind off super-loose. I always bind off too tight and have to fight to get the things over my heel