I am very experienced with solo trips. Just this year I tacked 3 days onto a work trip and did some stuff in South Carolina by myself. I have another trip for work in Toronto in Oct. I'll probably add on 3 days and sightsee. In the past, I've done Sedona, Grand Canyon, DL x 2, US Hollywood, US Orlando x 2, NY, Boston, DC, Vancouver solo. Probably more but can't remember off the top of my head. I have no problem doing things by myself, eating alone in a restaurant. And I love single rider lines! I am not an only child but introverted by nature. Most of my trips were work trips that I extended to explore the area.
Solo trips are good as you get to do what you want when you want. I like a mixture of trips with family and by myself!