The Grand Mayan is about a 45 minute drive from Acapulco. We arrived by Mexican bus from Ixtapa and were able to get a cab at the bus station. Taxi cab drivers are always around trying to get a fare and trying to convince you to take tours and site-seeing excursions with them. We did the Cliff Divers one evening and went into Acapulco another day. We shared the cab expenses with a couple (we didn't know prevously) on the way into town, and found our own cab back. We didn't feel in danger at any time. I have friends who love Acapulco and go there almost every year for a couple of weeks at a time.
The rooms at the Grand Mayan are wonderful, and the resort is very nice. We usually ate at least one meal at the resort. We took a cab to the grocery store and stocked up on food for lunch and breakfast. They also have a nice Internet service.
The time share sales presentation was one of the worst I have ever attended. The 90-minute presentation turned into an all-day affair. After the presentation, you're hit with another sales solicitation, which is really bad news. There is an entire website devoted the evils of the Great Vacations Club, which is different from the Grand Mayan Resorts.
Enjoy your trip.