There is DEFINITELY the WOW factor to the GV. We stayed in an OKW GV and also had 2 separate studios in 2004 for my DD's then 5th birthday family reunion bash. We had 13 family members (including us) and 4 friends (in the studio).
My kids still remember and ask when we are going back to our "house" at Disney 4 years later.
I must admit that I booked the GV for selfish reasons because "I" wanted to stay in one. In the end, like WebmasterCricket, I vowed "never again" at least with those family members. EVERYONE hung out in the GV and it was crowded and noisy with all the kids and adults.
It took 3 days before DH was fuming at his own family and threatening to "throw them all out" (only to me of course).
The funny thing is that MIL and FIL has been hinting (more than 2-3 times) about another such family reunion. There has been 4 additions to the family since that trip.
I have NO problems springing for the points. Even though time has blunted all the old scars and we no longer are vowing never again, we are not actively planning it either. It's one of those if all the stars align kind of things. It's hard enough when all the kids have different school schedules.
DH told his parents, that the family is welcome anytime, but the trips will have to be according to our vacation schedule. And if anyone wants to go just ask us when we are planning our next trips and we will try to work it out. He told them WE are not issuing invitations and making it a "mandatory" family vacation because WDW is expensive (even if the lodging is free) for his siblings' larger families and he wouldn't obligate anyone to spend that kind of money if they don't want to.
Sorry to be so long-winded but the bottom line is if we ever do a family reunion with DH's family again, we will either get multiple 2-bedrooms or if we do spring for the GV, we will get a separate 1-bedroom for US so that we have a quiet sanctuary to retreat from all of them.
Good luck with the planning!