I would prefer the same person for both cruises, but it's not necessary. The 2 cruises are totally different itineraries. I will be going to San Juan a couple of days in advance. I go on a cruise every spring and have a routine that works for me. I like to get up around 7:00, go to the gym, and then have breakfast. Then I go to the beach. I love the warm water. I prefer to have lunch back on the ship and then I go wander around the town. I get back to the ship by 4:00 and start getting ready for the evening. I will go down to the lounge and listen to the music, dinner at 8:30, show at 10:00 and gamble a little on my way back to the room. It can be a full day. I crash on the days at sea. It would be nice to have a dinner and show companion. Those are the times that I'm very aware that I'm alone. If you like the beach that would be great. I've scared myself taking taxis by myself.
I do drink, but not to excess. It's way too expensive on a ship anyway.