I second what everyone is saying. Is terrain park a necessity? If so check out Mt Snow or Killington. If not, then avoid like the plague. Is lift ticket cost a concern? If so, definitely check out prices and liftopia and buy >24hrs before you go.
I would highly recommend using Airbnb for lodging in a semi-central location of all the resorts you choose to ski at. Or use a travel site to search such as hotels.com. For example 2 years ago my family drove to VT for Xmas. Stayed in Middlesex. My brother and I skied at Jay (90min drive), MRG (30min), and Smuggs. Stowe is a 25min drive from there with plenty of restaurants and stuff to do. If you're lucky you can find cheap hotels in Stowe or Jeffersonville. I stayed at the Smugglers Notch Inn in Jeffersonville last year and it was chill. Bar and restaurant downstairs and plenty of locals to chat with. Smugglers notch is close. Town of Stowe is 30min away. If for whatever reason you go to Jay and need to stay overnight, I'd highly recommend the Snowshoe Lodge. Can only book over phone. Dive bar and dive motel. Bring own blankets cuz it's run down lol. Food is good.
I've never been to Sugarbush but it's right next to Mad River Glen so combining those two could be beneficial.
From my experience, on a pow day nonetheless, Mad River is the real deal and I bet your son would have a blast on all the natural features. Smuggs too. Jay Peak though is by far my favorite place in VT and has so much more to offer from a skiing variety perspective. Their glades are the tits.
I've found that 1 day isn't really enough to explore all that a mountain can offer. I would recommend 2 days at your top choice and largest mountain especially if you're gonna be hitting up the glades.
Not sure if you've been to VT or not but don't set your expectations too high. While it's still a blast, your conditions could be an ice rink every day.
Let us know what you choose and perhaps people could provide some insight on specific resorts and where to ski within them to maximize your experience.