Easy simplification:

Buy Wii if ur intending on local multiplayer gaming (smash bros., super mario etc.)
Buy PS3/x360 if u like more singleplayer stuff.

i had an x360 once, sold it because most x360 games is already available on PC, and playing solo games is better on PC since you don't have to share your TV with others. Bought a wii and am having fun playing it for get togethers n such.

Xbox Live, u'll have to pay to get to play online multiplayer if im not mistaken. PSN is free unless u go for premium stuff (not sure what). Between x360 n ps3, up to ur control preference. I prefer x360 since controller is big enough n firm.