I didn't get a WP pass this year but have ridden there for almost 20 years.
Mary Jane is typically the best side of the mountain. Lot's of mogul runs there, but in between the mogul runs are a lot of really, really good tree runs. Some of the best in the state. Check out the trees in between Outhouse and Drunken Frenchmen. There is a trail that goes into them from the top of the Olympic express and Zephyr/Eskimo express. From the top of the Zephyr/Eskimo area, just go into the trees on the left side. You might have to walk over to the entrance, it's marked. Right to the side of the top of the rope tow.
At the Mary Jane side, check out the trees inbetween Roundhouse and Columbine. If you stay more to the right side of that run, you should run into the hut Molly Brown's Tea house. It's not the most covert hut so if it's occupied I wouldn't take a safety meeting there.
Parsenne's Bowl if it's open, can be very nice. Especially running the trees under the Panaromic. They gladed them out and during and right after a storm they seem to hold the snow decently enough. Lot's of terrain to explore in there. It can be as wide open or as tight as you want.
I am pretty booked up during the time you are here. I doubt I'll be riding at Winterpark, but I may be up at Berthoud Pass (Winterpark lays at the base of Berthoud Pass) on one of those days. If you want to get some backcountry turns with Cody and me.