Hi Esther, have lots of fun on your cruise. Yes, 8 days is better than 7 days.
I think that all cruise ships are fun no matter where it is going to.
In Acapulco... make sure you take a tour with the cruise line because it will be safer for you. Acapulco is having some politcal problems so you need to play it save and stay with the tourist group. Don't go off on your own with a taxi driver unless you find a group of people to go with you. The taxi drivers will keep you all safe. But it is too risky for single women. Stay safe.
All the other ports are safe to go where ever you want on your own. You can walk around by yourself and still be safe.