I'd like them to go to something fairly big, a festival/large concert series, preferably one that isn't sponsored by corporations and has a political slant. Something like the original Woodstock but with more spikey collars? They have a nine year old so it has to allow minors, although they're not particularly concerned with it being 'family friendly'.
This is set slightly in the future, so even something smallish that still has Underground Cred could work, if it's likely to grow in the next few years. Starting in the US but travel is a possibility, since selling out pays well.
So where are they going? "Punk political vacation" didn't really turn up anything in google. :-/
edit: Oh wow guys, looks like I have a ton to choose from. Thanks!