I'm guessing a lot more games are fun on the Wii with other people.
hmmm, might have to rethink the wii, seeing as how i dont have any friends 
Yeah, I think the Wii is more an attaractive option if you have kids, friends or parents coming over who like to play games. I'm more a fan of Resident Evil, Metroid Prime and sometimes Super Mario Galaxy. Unfortunately the Wii has no proper racing games although Excite Truck is nice.
Games like Smooth Moves, Raving Rabbids, Kororinpa and Big Brain Academy are only played when more people play. Although my GF will sometimes play Smooth Moves or Brain Academy alone.
My 4 year old kid loves Barnyard, MySims and Excite Truck (and sometimes still the Wii Sports and Wii play games). I don't think a PS3 would have any playable games for him.
If I was buying a console just for myself I would rather have a PS3. But then I just as well play gams on my PC, so I probably wouldn't buy buy a console at all.