I would highly recommend doing a private tour with Rosie in Acapulco (see posts here). Zijuatenjo is very easy to do on your own, or just use a cabbie. Puerto Vallarta is very easy to walk around town on your own too, especially with a travel guide for things to see.
The Star was great (we were on her just before Thanksgiving). *Do* go to the alternative restaurants -- they were fantatic, food was excellent and service incredibly, We spent nearly 2 hours at dinner each night. Went twice to Le Bistro, once to Ginza, once to Cagneys and once to SoHo.