Like "Albert" says they will be very happy to take US$ from you at all of this ports. You also might consider buying Travellers Cheques in US$ as all the American owned cruise lines will change them dollar for dollar with a charge and as they are TCs they are more safe than safe cash. With the dollar conversion rate being so good at present they are worth holding onto for the future as well. Regards Neil Dow.
They will be happy to take your US$ off you in these ports - just remember you may get your change in the local currency so you can leave this for tips et.
Further to the answers, beware the VW beetle taxi drivers in Acapulco who will take you to their 'friends' boring shops. If all you want to do is have a bit of a wander, insist on going to the Cathedral square, send him on his way (in March taxi cost $3) sit & people-watch, go in the church, etc. You can walk along back to the ship & pop in the Fort if you want. In Costa Rica. a trip on the canals is leisurely & interesting.