Hey,
My suggestion is to talk to a couple of the mathematics/physics professors at your community college and see what their opinions are about UVA vs VT for a mathematics/physics major.
In addition, contact the departments!
Most mathematics/physics departments are always looking for a few more mathematics/physics majors and would probably be more than happy to answer your questions.
Finally, consider contacting some of the students, either undergrad or grad and ask them about their experiences and fields of focus at that university.
In addition, I am sure you are already aware of the tranfer articulation agreements for the Virginia Community College System (VCCS) which make the transfer process more seemless for the Virginia CC student. These are nice to keep in mind when applying to either.
Also, consider the following mathematics competitions since you are mathematics major,
The Virginia Tech Regional Mathematics Contest
http://math.vt.edu/events/competitions/Vtregional/index.html
The National "Putnam Exam" offered by the Mathematical Association of America (MAA)
http://math.scu.edu/putnam/
Lastly, if you can visit Virginia Tech October 20th, the Society of Physics Students (SPS) Zone 4 conference for the Virginia region and surrounding states will be happening that day with many undergraduates (physics majors) presenting at that conference. That should a good opportunity to get more exposure to the physics field and Virginia Tech (in all its physics goodness).
-PFStudent