Triple - Religion, Philosophy, and Greek. I didn't take any summer school, and I did it in four years. Big However - I wasn't premed, and some of those humanities classes fulfilled requirements for more than one major and the "common curriculum" of required courses for graduation all at the same time. I took most of my pre-med classes post-bacc, but I could have taken all of them in summer school as an undergraduate, had I wanted or been able to.
This program took some fenageling (where is my dictionary?), and I had to stretch some rules to make it work. I arranged a bunch of independant studies in which I read philosophy or religion in Greek, which counted towards my Greek major and towards one of my other majors. Our core curriculem required that we take atleast one course focusing on a non-european culture, so I took Asian Religions, which fulfilled the core requirement and contributed to my Religion major...etc.
Most people may prefer to take a more diverse spectrum of classes. The way I did it worked well for me, though, because I was able to develop a very advanced understanding of my majors, since I was the only person in my classes who could read some of the religion and philosophy texts in their original language. Also, by satisfying my core requirements with classes in or related to my field, I was better able to assimilate new concepts (those of Anthropology, for example) within a familiar context (Ancient Israel, in the class "Anthropology of Ancient Israel").
Voila
how long did it take you to finish?
