I've been to Maui and, while we liked it I don't have a burning desire to go back. I have a time share ( yea, I know) just outside Cabo and we go almost every year. We like the area so much we bought some land and are building a house - near La Ribera on the East Cape.
You don't say when but I'd hit Cabo November through May. The summer's down there get pretty brutal temp wise. The trade off is that's when the fishing and surfing are at their best. If you are into the party animal scene downtown Cabo is lots of fun but I've outgrown that a bit. We really like the San Jose Del Cabo area- just east of Cabo San Lucas, actually where the airport is. A bit more laid back, great restaurants and the "classic" old mexican town feel.
We've done the all inclusives in Cancun and we used them for breakfast, lunch and drinks. AI dinners are about as skip-tastic as they come. In an area like Cabo and San Jose with so many great restaurants from world class eateries to best ever taco stands there is no way I'd eat dinner at an AI even with it being included.