If the weather's right, Plattekill on a Friday is the best ... whatever's piled up Monday through Thursday is yours, along with 30 or 40 other skiers. It's great even w/o fresh.
OTOH you should really watch the weather and the Plattekill webcam re conditions. Even with fresh pow if there's no base built up, what would skiable be "dust on crust" elsewhere is "dust on mud/gravel/roots" at Plattekill. And it can go from skiable and perfect to melted off in one rain / thaw cycle.
As nice as it is on Friday's though, if crowd avoidance is a factor it's smarter to ski Hunter/Windham/Belleayre during the week and Plattekill on weekends.
Random points re Belleayre:
There are two parking lots and lodges - a lower mountain area that's beginner focussed, and a midmountain area. Unless you have absolute never-evers in your group, pass the lower mountain and park at mid mountain. You can ski the whole mountain from either, but if you park down below you end up having to ride some slow lifts and skiing beginner terrain for access to / from the more interesting parts of the mountain.
Another site to check for info on the Plattekill (and other Catskills) conditions is www.alpinezone.com
-- another ski forum with a Northeast focus, not so many members as epicski but all NY/NE skiers.
Belleayre is set up with a lot of similar looking runs coming off a long ridge. There's an area far off to the side at the top point of the ridge with a nice blue cruiser called Dot Nebel - I forget the name of the chairlift over there and other runs -- it has its own quad lift that tends to be less crowded than the midpoint in the mountain where the express quad comes up.