The spring sign ups for the clubs/organizations will be from 1-5pm at the MSC (memorial student center) I would suggest a quick trip through there before you go – there will be LOTS of students there & you’ll get a feel for the other things available on campus. You can park at Koldus building-University Center Garage (across the street) which is open to the public & pay via the machines ( it is an administration building with an attached multi-story parking lot) next to the stadium (Kyle Field). The bookstore is also in the MSC.
Walk thru the buildings (I think she wants engineering, correct?) - some will be open, others not. Generally students are friendly & will answer questions or help with directions (honestly our first trip here a student walked us from where we were lost to the building we were looking for - completely out of his way, happily did it & wished us well). Walk thru hullabaloo although you will not get access to rooms unless someone takes you, but you can always ask if you could see a room.
If you park at UCG, you could walk to the Evans library, then to engineering area , stop at Sbisa ( all you can eat dining hall), head to hullabaloo, and back towards MSC. If you like recreation facilities, go under the bridge to get to the recreation center. There are maps online & an app for your phone. http://www.tamu.edu/visitors/plan-your-campus-visit.html
Expect to walk - it is a huge campus. If by chance, she has already made up her mind based on other schools - the Bush presidential library is also on this campus & well worth a visit. (It is more like a museum if you haven’t visited one before).
It is a shame you won’t be here for a M-F tour, but given your trek from Baylor & UT you should see a difference between the schools even just walking around. Enjoy your day!