If I'm going to a resort anywhere (Disney, Carribean, Cruises, etc) I use a travel agent since there are multiple transfers and connections involved. I've found AAA to be very good at that and have good rates. Whether they are the best, I don't know. I used what ended up being some old lady running an agency out of her basement one time because she was cheapest and about every time and detail of the trip was screwed up. Have never had an issue with AAA.
For just flights and hotels, I usually go online, find who has the best rates in general, then call whatever airline that was and see what they can do for me. I have made reservations for up to 8 at a time. Did not get any group rate per se, but they were able to get us seated together which has not happened all the time online.