What's MEPS like for someone who won't have to do medical?

You are going to sit with a guidance counselor and they are going to make a phone call. They will get a list of jobs or a list of duty stations based upon the needs of the Army and the current business rules. You might have 1 option, you may get 3 options. After you make your choice you will sign some stuff, then get your finger prints re-ran and that is pretty much the extent of the day.
However as limited as your actions at the MEPS will be - it can still make for a long day. Bring a book and be patient

All I did was sit with the counselor and do a lot of admin paperwork. Then he worked on trying to find me a unit close to my HOR. Finally, the NG recruiter at my ROTC detachment pulled me to the cadet detachment at my school.

I was green on everything when switching from USAR to active duty and still had to go through complete medical at MEPS. But that was 2008 and for active duty commissioning so it may be different.