I am single, 33, and just returned from my first cruise on Conquest out of Galveston Texas to Western Caribbean.
Here is my opinion: I was in room 1207, bottom floor, 4th room from the nose of the ship. I was about 30 feet off of the water, had 2 portholes in my room which allowed a great view as we were entering into port, and it was the cheapest room left to book. Very much recommended. I would choose the room if I have the opportunity to go again. I could see the spray off of the waves as they bounced from the front of the ship.
As far as excursions, I took a Mountain Valley Rafting trip in Jamaica but could see the zipline above the river and they looked like they were having a spectacular time. I am afraid of heights so I had a great time watching from the river and getting a foot massage on the creekside. In Montego Bay I went to the Turtle Farm and swam in the lagoon with the fish and turtles. It was awesome for me but not really for the adventurous. In Cozumel, my other single table-mate and I went shopping and took a taxi to Paradise Beach. It was remarkable. It was my first time in the ocean.
Carnival did not offer any "single" events other than a meet and greet on the first night. With all of the chaos of the first night onboard, not too many people even knew that the event was happening. Apparently there were 2 other female single passengers who asked the cruise director if there would be any single events so he scheduled another singles meet and greet on Wednesday night but still no announcement. So, if you are looking to meet other singles, do some looking and keep up with your itinerary daily.
One of my suggestions for the end of cruise survey was that they need to change one of the lounges onboard to a singles lounge. Not for cruzing for guys but for singles who want to spend time with another single person who is not tied to a family for the week. I did need some alone, quiet time but also would have enjoyed having someone to hang out with onboard and compare life stories.
All in all, I would recommend going on a cruise to anyone looking for something different. You can stay in your room all week and order room service if you are looking for solitude and quiet. There are shows and other meeting events that could entertain people of all lifestyles. Or, you can sit on the deck for a week with an MP3 player an work on your tan.