Top Jax, Fiora
Bot Caitlyn, Ezreal and/or MF (Two different play style, but IMO if you want to play bot, you really need to know the three different styles these three bring to the lane.
Mid Karthus, Ryze (Karthus is all about farming, where as Ryze can trade fairly effectively after lvl 3/catalyst. Again, two different play styles to learn in the lane)
Jungle: Skarner and Hecarim Skarner, though some say he has dropped in the tier list, is still a very good jungler IMO. Hecarim is a move speed monster who really lets you develop ganking mentalities
support Taric (will be nerfed soon) and Sona There are the two supports you will see more often than not during League games (up through mid-gold at least). Two very different skill sets, but the same style of agressiveness or defensiveness depending on the complications that are bot lane matchups.