If I had the cash to throw around, I would just grab the Nintendo Wii and hold onto the X-Box. Otherwise, here are my answers:
1. Myself and the wife will be using the Wii. She loves classic Nintendo games as well
2. I grew up on Nintendo systems, so I tend to favor puzzle, action/adventure RPG's and first person shooters (not as much as I used to, though).
3. The sensor controls are what interest me the most. i have a lot of fun when I play at my friends, and the idea of actually breaking a sweat while playing a video game is enthralling.
4. I do care about graphics, but I'm no longer OCD over it. My hardcore gamer days are passing me by, and I have a lot more fun playing the Wii than the Xbox.
I guess I want a more social gaming system, and the Wii seems to fit me the best...