Just a thought

All members who say they are 90% sure (stuff happens) should write in and state they are interested and the number of quests they would bring.

This would help answer 2 pertinent questions. How many to inquire about reservations for and also give you a better generalization of a suitable, centralized location for all.

Then pick three "fun" places or resorts from the centralized geographical area that was ascertained and then come to a consensus of where to meet, after investigating all the relative amenities.