Depend on the skill of the player but usually an equally skilled player do take hours as you say. I enjoy more playing co-op battle with your friend against an AI. Customize a map with more advantages on the AI than you. It's quite addicting. Olaf is imba...
I like Final Fantasy Crystal Chronicles, Mario Kart DS {Really good} , and Metroid Primes {really cool wi-fi battle with friends}, of all time I think the best is Metroid Prime if you had a lot of friends with DS
Kingdom Hearts is fun to joke around with your friends, Mario Kart is good for the challenge, Metroid Prime is fun for the lulz, ... We all know though...the true ruler of multiplayer fun. Clubhouse Games. *gets shot* D:
Bomberman (8 player with a single cartridge... WOW) I really want to try a game with other 7 players Mario Kart Kingdom Heart 358/2 Days (but since my sister doesn't like this and i can convince her to begin such kind of game, it's hard form me to find someone to play with)