To the OP -
I guess the question is why you are doing a Post-bac program to begin with. If your GPA is low, then med schools can easily assume, right or wrong, that you did not work hard in undergrad. It then begs the question as to why you need more time off.
While taking classes during this upcoming year isn't a bad idea, it is essentially like doing a Post-bac program. I was able to work at a university doing research after undergrad, and then I was able to take classes at the school for free (free for undergrad classes, needed to pay the taxes on grad school courses).
Just remember, that if you are only taking a 'few' classes, you will NEED to get all A's (again, assuming your GPA is low), since all you have is 'free time' on your hands.
I suggest that whatever you do, go at it 100%. Don't do anything half-assed, as adcoms will see right through you.
Good luck!