I think the date is far enough out that most people should have an open schedule. I've organized a fair number of Mexico surf trips, etc. in the 10 - 15 person range and from my experience you'll never be able to find a date that works for everyone by looking at their calanders. You always end up in a situation where Bob can't make one weekend and Jorje can't make the other and you have to choose who will be included.
Instead you have to pick some other criteria for deciding the dates, announce the dates for the trip and then find out who is in.
I think that we should first settle the powder vs corn question. Powder is powder and we all love that, but there's a real chance of getting snowed into cabins with a bunch of dudes or having unstable avy conditions. There are much better odds of getting big lines during corn season, but corn ain't powder. I personally lean toward corn. Powder is best scored with a flexible schedule and an eye toward the weather.
Once that's settled, we could consult the weather records and some experts in the area such as Ron from TPR, Sue Burak from the Avy Report, etc to decide on the best weekend for good conditions. Then set the date and ask the question... In or out?
Yeah - I think p420 should just pick the dates, if he's willing. I think the exact dates aren't so critical in the spring, anyway. Jimw suggested end of April/early May. Maybe burn some incense as an offering...