Your travel buddy/buddies can make or break your trip!
Anecdote about how a buddy made my trip: I spent an entire summer in Europe with one other person, who I didn't know very well at the time. We both thought it would be OK/awkward, or worse case scenario being we would not get along... To our surprise, we traveled really well together. We had tons to talk about as we got to know each other, and realised we had very similar travel styles. We butted heads from time to time on money-related issues but they were pretty minor issues in the scope of the entire trip. Towards the end of our trip, the one thing I NEEDED to do in London was watch Les Miserables the musical, and told her I'd meet up with her after the show because I had wanted pretty good seats, which could be costly, but she was down to join me. If you're traveling with someone, and you have a 'must see/do' list, make sure your buddy is okay with tagging along, or okay splitting up and meeting later.
It's always better to over-communicate than not. <-- can be applied in most situations; that's some life advice for you, on the house ;)
Take my quiz below to see if you and your buddy would be a good fit: