Even though I have been out of skiing a while and am getting back into it this year, I always keep up on the local buzz. I have skied all these places and am very familiar with the terrain, improvements, etc. as they are all fairly local to me, living in the Hudson Valley/Catskill region of NY.
I hate to ski Hunter on weekends! It's been awful since the 80s. Everyone and their brother from NYC and the tri-state flock there, especially since the town has a jumpin' nightlife on weekends. Gets a lot of the hard core party crowd and newbies following the s/o's up for the ski/party scene.
Wyndham is a less crowded (but has picked up a lot in the past 10 years) alternative to Hunter, and word is nearly, but not quite as bad on weekends, more family friendly.
Plattekill is a great mountain!!! Nice to see it get some mention here. Not as much snow making and I understand the lodge area is not as developed as some of it's competitors, but if you like to ski, this is one off the beaten path mountain worth a look. Definitely NOT a beginner mountain, IMHO. The terrain is the most challenging of any of the "local" Catskill terrain I've ever skied. This used to be a favorite of mine in college. Ticket prices used to be a bargain here, but are pretty competitive now, even though they don't have 100% snow making. Because of where it's located, tends to get more natural coverage they Hunter does. I understand they are continuing to make improvements here from my friends who took a drive up there this summer for biking event and was really impressed with the vertical drop here. I would say definitely a worthy trip for an advanced intermediate/expert skier who wants to avoid weekend crowds.
Bellayre Mt. - this was closed for a while way back when, before the state put in snow making and decided to develop the place. Reopened with a lot of improvements. Most of the runs run straight down the face (not as interesting as some other areas, but decent), not too many meandering type runs, but mid-week not real crowded (weekends, they bus up from NYC, and I would stay away) and some great deals. There is one 5 day period in Feb and several week days through out the year they are offering $10 and $15 lift tickets this year, which is a good deal and I hope to take advantage of... This is mostly an intermediate to advanced intermediate mountain.
Mt. Peter (10 -15 minutes from me, off the Appalachian Trail) - This is where I will be doing my women's clinic weekly. Very family friendly, not over crowded. Ironically, I think it is one of the oldest ski ares in NY state. Small, but has a little of all terrain, good snow making and good ski program which offers lesson free to beginners of all ages on weekends, in two hour increments, 4 times day each day on the weekend. If you are bringing kids/newbies to the slopes but want to ski yourself...and don't want an overwhelming crowd, this is the place. You will find a lot of kids/families though. Weekdays are VERY quiet, almost desolate, so I look forward to my women's Thursdays to just work on my skills.