But if you go by yourself you need to be okay spending a lot of time in your own head. On the plus side, no constant negotiations on how far, or how fast, or where and what to eat, or where to stay.
+1. I have done most of my touring alone and have been on the road alone for as long as nearly two months. You really do need to be comfortable with your own company to spend a long time solo. And being able to make your own decisions is a real plus.
I will also bet that solo travellers receive more "acts of kindness." My very first tour started out with ACA's group tour across the Northern Tier. When that part of the trip ended, I rode home solo in about three weeks. As a group of a dozen, we seemed more self-sufficient when together in camp and thus were rarely offered assistance. During my solo trip home, I was offered things several times, including a half a pie that a woman had baked in her RV. During the group portion of the trip, it would not be odd to find yourself riding alone. It was then that people were more likely to experience acts of kindness. One woman in the group who was riding solo one day was invited into the home of a woman in rural ND and served tea.