Patapon
Me and My Katamari
Metal Gear Solid: Portable Ops
Wipeout Pulse
Final Fantasy VII Crisis Core
Prinny
Those are all pretty long games with tons of side stuff to do. Also they are insanely fun.

First one to look at is Dissgia. It is a cartoony RPG but can last for ever. You are a son of a great demon trying to get your kingdom back. It is turned based and customizable for weapons and party members. I have spent over 100 hrs on mine and still going.
Another one to look at is the Monster Hunter series there again you can customize your person however you want. Armor, weapons and such and going after monsters that are 4x bigger than you is just a thrill.
These are just my suggestions and some to look up to spend your time.

Were you ever a fan of the MegaMan Series? I’ve had MegaMan Powered Up for 3 years and still play the game simply because of it’s level editor. I like to make levels, but you can also download thousands of levels off the website you can connect to through the game.

N+ is epic and addicting. You are basically a ninja maneuvering obstacles like mines, turrets, and to get to the next level…N+ is also for the 360 and DS http://en.wikipedia.org/wiki/N%2B

Long games…?
Monster Hunter Freedom Unite –> 500 hours of gameplay
GTA Liberty City Stories
GTA Vice City Stories
Dissidia: Final Fantasy
Rock Band Unplugged
DJ Max Portable 2

Patapon 1 and 2, Star wars battlefront series, monster hunter freedom, Gta vice city stories

castlevania
i haven’t seen my bro for ages, lol

God Of War Chains Of Olympus will keep you occupied for ages and is fun!

you may want to try rpg, Crisis Core: Final Fantasy VII

Grand Theft Auto Vice City Stories

i’ve been playing star ocean 2 since playstation and got it for psp