I have been going to Killington for more than 20 years now and agree with many of the reviewers here. Family friendly and crowds are sometimes an issue at Killington becuase it is accessible by so many east coasters (I live outside of Philly). It is unfortunate the lift ticket cost is now so high, too high in my opinion, that makes me consider other options more often.
Killington has amazing variety, typically good snow, and is overall the best mountain in the east in terms of size and variety (Okemo for instance, does not have enough faces to make it interesting). If you are an advanced skier and can stay way from the bottom parts (Rams Head) than Killington is great.
People, don't write bad reviews about the ski area becuase you had a bad bed or stayed at a crappy place. While that does suck and effects your stay, it doesn't directly relate to the ski area, so keep the review of the ski area to the area itself, and just add on 'I don't recommend staying at X...".