As I mentioned before, Tech is one of the few schools the offers both tours and an open house.
Someone mentioned yesterday they'd been on a tour there, that the building was pretty empty, and they just meet a couple of student tour guides. That's what tours are going to mostly be like there. They take place after the school day is over so most had emptied out. They used to offer 8am tours as well, which gave a better sense of what the school is actually like, but stopped those a couple of years ago.
The open house gives a far more realistic sense of what the school is like. They actually do a terrific job of having teachers and kids from each major in classrooms so you can ask specific questions - very helpful. The principal speaks in the auditorium for a bit (I've seen the entire thing fill up and it holds 3100 people) and then you're given a list of who is where and you're free to wander. Aside from seeing faculty and students, which is great, it's a chaotic, overwhelming mess, which is also great as it gives a truer sense of what the school is like. 4000 or so people show up for the open house. Hallways are crowded, so are staircases. Much more realistic view of what Tech is like during a school day.
Having said that, the open house is the week of the SHSAT, on a school night, and is pretty intense. I chose to do tours with both my kids and when I went to the accepted students open house I basically begged my daughter not to go - I was so overwhelmed. But it was her first choice and it turned out to be fine in the end.