Wii is the only console I have atm. It would definitely be secondary to a ps3 or 360 if i had one of those because the Wii just sits there. I'll end up selling the Wii and probably getting the ps3 because I can't go on playing Brawl forever.
I'd advise against getting a Wii. It's the only system I have at the moment but i plan on selling it because it just doesn't have many great games (I have Brawl, Galaxy, Zelda, MP3, No More Heroes, Paper Mario, Zack & Wiki, Fire Emblem and Strikers, which are probably the best games available for the Wii) and I'm thinking of getting a PS3 because RE5 and MGS4 look too sweet to miss. I'm a huge SSB fan and was psyched about Brawl but was kind of disappointed with most of the changes made, so it's not really making me want to keep the system like it did before i bought it. And although the first party games from Nintendo own, I doubt there will be many upcoming games that'll blow me away (I could be wrong). MadWorld looks decent, but eh. In the end it's up to you, but i'd get something else.