I have all three consoles and I can tell you this: There are gaming experiences that the Wii offers that you can't get anywhere else. The Wiimote is cool as hell.
That said, I feel like Nintendo made a huge mistake not putting just a *little* more graphics horsepower in the Wii. My daughter likes her Wii but when we have a choice -- i.e. Lego Batman and Lego Star Wars Complete Trilogy -- she always chooses the 360 over the Wii because she likes the better graphics.
The 360 has become more casual over the last year and unless you really feel like you need the Wii Experience, I'd go 360. Get an Arcade and buy the refurb 20 gig hard drive for 20 bucks from Microsoft. There are a lot of arcade titles that are VERY casual and there are many more in the pipeline.
Really, though, it comes down to the games you want to play. After playing a game like call of duty, Forza 2, Gears, Lost Odyssey, Bioshock, Mass Effect, and so on, going back to PS2 style graphics really blows chunks. Yeah, Super Mario Galaxy is a beautiful game, but the truly impressive graphics on the Wii are few and far between.
I hate trolls.
Systems I currently own: 360, PS3, Wii, DS Lite (2)
Systems I've owned: PS2, PS1, Dreamcast, Saturn, 3DO, Genesis, Gamecube, N64, SNES, NES, GBA, GB, C64, Amiga, Atari 2600 and 5200, Sega Game Gear, Vectrex, Intellivision, Pong. Yes, Pong.
