Was just in Calica last week. Be prepared before you dock, Calica is a gravel pit. Seriously, it is a gravel pit. $20.00 round trip for a taxi into Playa Del Carmen. Xcaret very close, and Tulum a little farther, but definitely driveable by taxi.
Tours are offered to Tulum, Cancun (City and Shopping Tour), Xcaret, Snorkeling, Beginner Scuba, etc.
Xcaret is really the thing to do in Calica. Actually, unless you travel it really IS the only thing to do. <LOL> Seriously, it's a great way to spend a day. There are animals to see, a butterfly farm, horseback riding, a dolphin swim, snuba, a beautiful lagoon to swim and snorkel in, the underground river to float down, a couple of yummy restaurants, and lots of stuff to do.
A big recommendation is to buy the excursion through the cruiseship. Typically the price is the same as the gate admission, but it includes shuttles to and from the ship all day. We played in the water all morning at Xcaret when we were there, went back to the ship to eat and shower, then went back to Xcaret to walk around, enjoy the sights, have a drink, and enjoy the live music.
If you want to shop, definitely take a taxi into Playa del Carmen.