Dont' bother with GRAW 2 for 4 player action on one console, it is terribly laggy. 3 player is better but the game runs best with just 2 players on one screen.
GRAW on the other hand is ok, no problems at all. If you have never played GRAW then get it as it is only £25 now WITH Chapter 2 which has extra missions and gun. If you have ever played it though you won't notice the add- ons.
Both are very good games single player though.