Many moons ago, I had a Roscoe canoe (for 2) but I found it difficult to get my wife out in it. She loved to go out, but trying to coordinate suitable times was a major problem. So, when it came to getting a yak, I thought 'double' as then my teenage son or wife or somebody may be able to go. But, on the other hand, if 80% of the time I was gunna be by myself or with others with singles, then the extra weight and grunt needed to paddle it would be a pain. So, while I originally thought I was being very selfish, I ended up with a single yak, a small one.
My teenager loves the yak but when it comes to him actually using it, like on a family trip to the beach, he usually doesn't bother. The water is too cold or the sun too hot, or whatever. In fact, getting him on a family trip to anything is very difficult nowadays. If we take him and mates, even a tandem yak would not be enough.
Getting a single was for me the best choice.
Now while I saw a nice tandem with a guy and gal on the bay the other day, in my opinion, I think most people would do better with two singles than a double. If ya really sure ya can drum up a co-paddler, then maybe a tandem would be cool. But, you also have to be able to work in with them as ya work pretty close to each other. I find that singles allow people to talk and also do their own thing. This type of decision has been written up previously on the forum, so you can search and find more discusssion on it.
There's also past posts on the Swing and Esprit, so worthwhile doing a search and seeing what ya can pick up there. Both boats, as far as I am aware would be excellent. They can do the dams and ocean with no problems.
In the end, you make the decision on what is right for you, but it is very helpful to get other folks experience. All the best with the decision making.