I currently go to school in Cleveland. I'll have some free weekdays coming up in early December. I'm wondering if anyone has been to Peak n Peak or Holiday Valley / Holimont, and would give a recommendation as to which area is better to ski at. Also, not sure whether it's possible to ski Holimont since my understanding is that it is private.

We ski the Peak at least once a year because my wife is from that area and we get together with her cousins.  It does not have much vertical (400 - 500?).  If you are looking for advanced trails and long trails you'll be disappointed at the Peak.  

If you are into parks and features they do a great job of that.  They had some monster jumps last year.  They also set up a BMX style course / slope that was pretty cool.  Check out the last video here.  I thought that fun and unique.  They also had a jump that landed you in a big airbag.

We have fun getting together with the family for a day of skiing and goofing around on that course / bag jump.  Tickets are reasonable and crowds are very small.  Last year we went over NYE and skied right up to several lifts.

They have a couple bars / dining options on each end that are OK.  

Note that Holimont is closed to the public on weekends when it is members only. During the week it is open to the public. I have not skied Holiday Valley or Holimont, but I am told that they have terrrain similar to Seven Springs. The nearby town of Ellicotville is supposed to be a pretty cool ski town.