In my opinion, there are a bunch of games that I have played that I can go back to and have fun, like RE4, Fight Night Round 3, Resistance- Fall of man, GTA4, GTASA, etc. Name games that you have played that has a good replay value, and is still fun to you.
Pretty much any Zelda game I've played, Final Fantasy X, Star Wars Battlefront (first and second), Puzzle Quest, Animal Crossing...
I have no problem replaying games a lot, assuming they're good enough that I want to replay them. I've never understood the whole "I've beat it so I'll never touch it again" mindset.
Fallout 3
Diablo games
LOK series
Starcraft
Age of empires series (mainly 3)
WoW
basically the most re-playable ones I find are either those with great storylines (LOK series) or those with RPG elements, for example Age of empires 3 has the "home city" system, so although its a pretty good RTS, the Home city system makes it unique and gives the player a reason to continually to play games other than prestige. RPG's in general that give many options to players as well.
i'd have loved to play those online, but lucasarts made a real mess of things by not bringing out a proper patch for the dvd version meant i couldn't... idiots...
My brother and I play against each other all the time, or with his friends. The time I accidentally stepped on Darth Vader while in an AT-AT still remains one of our top "what the hell did you just do?" moments while playing games
most fun i had was in co-op galactic conquest (we had it on ps2 also). i never felt more smug than i did when i flew a perfect circle around an at-at's legs with the tow cable attached... and then i had to fly away, so i had to try and watch his part of the screen and mine at the same time as it came crashing down...
maul was insane at times. though, i have to say, i used to love playing on the death star was rebels (or any jedi). the long corridor (where they had the gun fight in a new hope), just chucking the light saber down it, used to rack up kills... that and the second shuttle bay... 100s of kills easy...
I've just always been a fan of the Empire in the OT I have a decal of the Imperial insignia on my car (along with the Triforce). I've always found the bad guys more interesting in Star Wars.