just from those 3 suggestions i think oblivion is fun. i've played it and it really does waste a good month or two. mass effect is awesome and for an rpg it is rather short even if you did just about everything maybe 2-3 weeks, less if you were like me and had no summer school

i'm playing the witcher right now, it's a nice game but the problem i have with it is some of the quest are really confusing and you can have a hard time figuring out what you are suppose to do without a guide. and unlike oblivion you can't fast forward time in this game unless you decided to pay an inn or freeload off a friend.