Killington SUCKS for snowboarding. Too many flat areas between the six so-called "mountains," which are actually just bumps along the same ridge. And the people there are 90% New Yorkers, mostly the rude kind yelling at their spooled brat kids for not having enough fun. They lie about their trails and their snow...yes, every mountain uses "marketing speak," but Killington is by far the worst, claiming tiny crossovers as trails, and saying they have a foot of powder when it's likely raining. Oh, and they don't have the most vert, either, unless you count unstrapping your board to walk across a parking lot to pick up a flat snow-shoe trail down to the Skye Ship base.
Stowe is awesome if you want to advance your skills. Very long trails, and some of the steepest in the east when you're ready to test how big your balls are. Plus, there are two distinct mountains, Mansfield and Spruce Peak. Your lift ticket covers both, and there is a gondola to take you back and forth between them. It can be spendy, though. Look for a ski club deal.
Best place for a great weekend is Jay Peak (no "s"). Like a mountain out west, with lots of glades for all ability levels. They just did tons of expansion, including a huge indoor water park with a FlowRider (stationary surfing wave) and one of only two loop chutes in the country -- you literally drop straight down for about 50' before doing a loop like on a roller coaster. Open till 10:00 pm, so you can board all day, then hang out in the water, the two combined are cheaper than a one-day ticket at Stowe. BUT, you can't go wrong with either. Both Stowe and Jay Peak have awesome terrain. Stowe is actually a town, a miles-long strip with lots of motels, bars and eateries. Jay Peak is a big, self-contained resort with a couple of hotels, a pizza joint, a few restaurants and bars, even a surf shop and mini market, miles from civilization.
You can't go wrong at either, IMHO. Further down the list, depending on where you are, hit Stratton or Sugarbush. Bolton Valley isn't bad, either, especially with good snow. BV and Sugarbush are all in the same general area as Stowe, so if you get a cheap room nearby for a couple of days, you can take in a nice variety of terrain. In Southern Vermont, Mt. Snow can be fun -- it's not super tall, but there's lots of terrain, nothing seriously steep, good party vibe. But go mid-week. Because of its proximity to CT/NY, it gets crazy-crowded on weekends.