So what's really more important? Is it worth taking a few easy classes to boost my overall GPA or should I just concentrate on my science GPA and get that as high up as possible?
I wouldn't worry about this too much, you really should try to make sure they are both high. However I've heard from users on here that ADCOMS consider Cgpa a little bit more... But overall you should really try to have around or higher than the average for accepted students : 3.7 Cgpa / 3.6 BCPM.
The great thing about taking more science or math classes, is that As in them will raise both cGPA and BCPM GPA for MD schools. DO schools don't include math in their sGPA, though.