Yes, riding solo is more fun (ie. faster), and easier. It is a lot of work carrying the extra weight, making extra bathroom stops, and all that.
I actually enjoy spending time with my wife, as she is my best friend. No nagging, no moodyness, just good times. She like adventure, camping, and beer. She has expressed interest in getting her motorcycle endorsement, but is not willing to commit. While I didn't discourage her, I was worried about her riding on the street. She just doesn't have the attention span required for safe street riding. I tried very hard to hide that fact, because I wanted it to be up to her. She does fine off road for short distances, though, so we ride separate bikes sometimes in the forest. She has even riden the 750 Aprilia off road, and didn't crash it (but came close
2-up riding on the street is worth every bit of extra effort, especially with an intercom system. If we can talk while riding, it keeps her alert, and allows her to be an extra set of eyes for safety. From her point of view, it also keeps me from riding like a maniac.
I ride about half solo, and half 2-up, so I'm pretty happy with the arrangement.