But that said, I just took a four day trip to Germany by myself and I loved it. I think I spoke less than thirty words to anyone on most of those days, and found it tremendously relaxing to just walk around a museum by myself, alone in my thoughts. I took a three hour train ride to Poland just because I wanted to, and I loved sitting there by myself watching people in rural East Germany go about their business. It's a lot more difficult to be a fly on the wall when you're with someone, because the minute you open your mouth it's evident you are an outsider.
But on the other hand, I'm extremely reluctant to approach complete strangers and strike up conversation. When I'm with someone, it happens naturally. When I'm by myself, I will be alone for the duration of my trip.
On the other hand, I know people who love to travel alone. They might disappear into Budapest for 2 weeks and tell tales of how awesome it was when they resurface. It depends a lot on the individual.
I'm from Europe, and find travel alone in Europe a little dull.
Travel in Asia is so interesting, I prefer it alone.
I really wanted to run the Disney World Marathon last year, but I couldn't get a group together. If I had decided to pass I would have missed what turned out to be one of my favorite trips ever.