I did a three month RTW trip solo in 2005. I definitely did not get bored - but I also kept up a stiff traveleling pace, hitting 19 different countries in that time (counting land routings). I also had a lot of people come out of the woodwork saying that they knew someone in one place or another, which resulted in meeting random people in many places I went. In places where I didn't know anyone, I was young enough and poor enough to spend most of the trip staying in youth hostels. A nice thing about the hostel approach is that they are filled with people who are generally in the same situation of either travelling alone, and typically very interested in anything from a short after-dinner conversation to spending a day or two with you as a travelling companion.