I've coached at three of the programs mentioned in this thread, and have a U14 and U16 of my own in a program now.
Things that I think ski parents should think about that I don't see already well-covered in this thread: 1) do you want to ski while the kids are training and if so, is the mountain one you like? what about the town if you're getting a ski house nearby?; and, 2) as of late with the consolidation of ski area ownership, how is the mountain being managed?
With respect to point 1, there are some mountains that have great race programs but I'm not sure I'd want to spend a season, as a parent, skiing and living at that hill every weekend. As to point 2, some Vail-owned mountains really struggled this year in providing their affiliated race programs with hill space. Attitash couldn't set actual gates until January, if I recall correctly. Wildcat is woefully neglected. Rumors were swirling about Vail's plans for Crotched last season. Some of that was driven by the unique circumstances of COVID, so hopefully Vail buckles down, fixes their employee issues, and comes back strong.
Random thoughts on a few different programs:
Wachusett offers a lot if you decide you don't want to get a seasonal rental at one of the bigger mountains further from Boston. The mountain is run incredibly well, but the race program is quite constrained in terms of training time, and it's hard not to get bored if you ski there when your kids are training. They had some sort of problem with the homologation of their GS trail last season, which was a big bummer that I hope gets sorted out.
Franconia Ski Club has one of the best training venues I've seen anywhere, and the new performance center is fantastic. Having the race program separated off from Cannon by being at Mittersill is a HUGE plus. I'm a big fan of having a dedicated T-bar on a race hill for getting in lots of laps, which is effectively the case at Mittersill, and Sunday River. The FSC vibe is definitely a bit more intense than other weekend programs, and I've seen them turn out some incredibly good racers but also burn some kids out. Getting a rental that's actually IN Mittersill and training with FSC is pretty awesome. If the culture is a good fit, the only drawback I can really think of is it seems Cannon focuses their snowmaking over at the main mountain before they push to open up Mittersill, so gate training gets pushed back further into December than some other hills.
Waterville seems a small step down in terms of intensity from FSC (talking about the BBTS weekend program, not the academy), pretty good venue though more prone to lift holds and some other issues. Just under 2 hours from Boston is a plus. If you have kids that may want to step up from a weekend program to doing a winter term or academy, Waterville seems to offer that path.
Loon Race Team is one more step down in intensity from Waterville, but still a strong program that is perhaps more family focused. They're doing a winter-term program this year with the Linwood school. Loon is a well run mountain that gets crowded on weekends but the ownership is investing heavily in improvements (including summer downhill mountain biking), and seems to support LRT well in terms of opening up training terrain early. Lincoln is a pretty good town to spend a winter's worth of weekends in.
I've heard good things about the program at Ragged Mountain, which I think is a bit of an overlooked gem of a hill that's closer to Boston than most of the bigger mountains. Great lodge you can always find a table in, fun race hill, it's never been too crowded when I've been there. One drawback is there's nothing else around the mountain, so no "ski town" if you're renting in the area.
Sunapee seems like it has some great people working in their race program which I think is pretty big, but it's a Vail mountain that catches umpteen billion Epic pass holders that don't want to drive all the way to Stowe. The shortest drive from Boston to get to a big race program. Get there early!
I've been to a bunch of races at Gunstock in the last couple of years, and I think that place is kicking butt though being town or county-owned they're dealing with weird, local politics standing in the way of making some needed improvements. They do a great job with races, nice overall vibe, and I'm a sucker for the view of the lake.