It looks like you've got a pretty tough schedule as it is... I would go with the less tricky one. I know AP Calc AB has given a lot of smart kids at my school trouble...
I agree. Having a hard schedule as an undergrad is not going to improve your chances to be admitted. It won't improve chances because you would be less likely to maintain a high GPA, which would hinder you. But, if you can do this, that's great. But, they never pay attention to the rigor until after you are interviewing, if they look at your schedule.
Example:
You- have a 3.9
and took biochem and human infectious disease at the same time as a freshman and then you continued at this pace.
Another Applicant- he/she has a 3.9 as well, but they majored in english and don't have much science classes under their belt and actually made a C in one of them their senior year.
I would think that you would be more competitive. But, that's just me.
Now, the likelihood of this happening is very slim. So, my advice is to avoid the low GPA and go with some easier classes your freshman year. If you read my other forums you might understand better. I crashed my freshman year because I took a senior level bio class with ochem (not a good idea).
Plus, you would be more flexible because you wouldn't have to study so much. The only hard classes I am going to put my self through from now on are bio classes, because I think they are interesting. But, now, all I have to study constantly are the bio classes and not spend 8 hours a day in the lib. I can research comfortably a join some campus groups. It is great to be free after such a rigorous schedule.