What are the best travel organizations out there for loan travelers?

I have always wanted to go traveling but have never had the time or money or commitment from other people, now I am really starting to look into it because of something I read.

I have searched a for some organizations that allow loan travelers to travel with groups of people but have given up before I can get enough info because they don’t offer the things that I am looking for, cheap travel to more that one destinations with other people.