Good choice. I was about to add to the chorus of AV haters.
To me, AV is a worse Monster Bash. It shoots badly, the rules are unbalanced for score competitions (shoot Hawkeye all day), and the modes are all tedious as all get out (shoot the same shot 7-10 times, woo!).
Mostly, though, it's just really badly balanced scoring-wise, and that drives me nuts.
IM, though, that thing is sweet. Brutal, but you can help that some with setup if it's too hard for your family. There's real decisions to be made, objectives to go for that are hard to achieve, and then some great wizard and mini-wizard modes...