First, you need to realize that if you met someone at the tour guide office, then you are automatically meeting "go getters" or "amped up" people. Second, no matter where you decide on attending college, there are going to be overwhelming people, not everyone is straight chilling. I think it is also important to acknowledge the town GW is in. DC, as it is, is a very polarizing place but also accepting of different views, regardless of how Congress may act. There are students at GW that are very passionate about issues, places or things, and that passion is what makes GW so special. It serves as a forum for spreading new ideas and updating methods of tackling old issues through student engagement and distinguished speakers/professors.
What is it like to be a guy at GW? There are several ways to address this question, mostly has to deal with what you are looking for. To start off, the campus is very welcoming to all sexual preferences. If this is something you consider with "what its like to a guy at GW" then have no fear. To your point of only meeting female students, one factor I considered in picking GWU was the fact that the ratio was 60% female to 40% male. Beyond the obvious female majority at GW, there are plenty of activities, events and sports bars in the surrounding area to achieve any "guy" objectives. In trying not to come across as chauvinistic or sexist, there are a lot of attractive women that attend GWU. Thurston Hall may not be the same while I attended in the mid to late 2000s, there will still always be a party to attend or people to hang out with on any given night. Just don't get stuck on the Vern.
If you are into sports, GW has Division I varsity programs that you can try out for (contact the coach in advance), and there is a lot of intramural sports/tournaments that you can join in as a single player or form a team. While GW knocked out the only thing that could have been considered a sports bar, "WOW" ("World of Wings"-RIP), you'll be a stones throw from a number of other bars, all of which will have TVs and games on, given the season. If you are into art, history, politics, there really is not a better college for you. GW is the only university actually inside proper DC, right next to the National Mall (i.e., museums, Washington monument, memorials and WH). There is always something to do. Unless you actively try, you won't go bored.
Bottom-line, you will have fun and experience the best of life at GW.