Though I haven't really played any new games since the N64 era, it doesn't get much better than the old school NES and SNES games for me.
NES games were simple, addicting and fun. The SNES of course added better graphics and sound with the best console controller ever created before the world got stupid and complicated everything with analog sticks.
I can play those old NES games over and over.... Mario, Contra, Gradius, Excite bike, dr mario, punch out. If you ever get bored, grab some beers, get 10 of your friends and have an old school NES tournament
It can get pretty intense. I hold the record for the most ownage in contra staying alive to the last level on one life (though I didn't get a chance to finish... I would have beat it on one life grr!).
SNES has some of the best games ever created, Mario World, Mario Kart (10000x better than the N64 one), etc. Top Gear anyone? And of course the best game of all time, Chrono Trigger.