If you group isn't very large, deck 10 or near the pool is good, but it's difficult for a large group, as there ARE other people there too.
I've been to two very large (over 50 people) DIS meets at Promonade Lounge and that seems to work very well. There's room to mingle, a bar and bartender you pretty much have to yourselves and there is no problem trying to locate the rest of the group. A 3PM meet works well...enough time to say hi and chat before heading back to your staterooms for muster drill. Some of us would then arrange a spot to meet for sail-away if we wished.