I've been thinking about it for a bit and gone through a ranges of players and back again. I think you need at least 5 recognised bowlers, and a good mix. I don't understand those who pick two keepers if there are noticeably better batsmen about. I also agree in part with MM in Gayle would be a good choice. I am picking this on a decent batting track, no hint of rain (so will last 5 days) and turn in the 4th innings.
Gayle
Smith (c)
Trott
Amla
Kallis
Watson
De Villiers (w)
Swann
Steyn
Harris
Ajmal
There are a couple of names there that might be a bit left field. Harris has shown he is a good bowler.
I also have Watson. For all his faults, he is à decent all-rounder and fielder.
One off game, so Gayle can go ballistic and is my part-time spinner as well if Swann and Ajmal are not firing.
Trot and Amla to grind the opposition down for a couple of days.