I haven't read all proposals but i might suggest gathering in Estes Park , CO. You have plenty of room for any size gatherings, camping or hotels. plenty of riding options- twisties, hwys, mtns , altitude , nature. rocky mtn natl park- trail ridge road, mt evans(one of my favorites) all types of mtn passes / hot springs within days ride. don't think any rider would be disappointed. your also pretty central to a lot of areas i saw mentioned. good luck on decision.