Penn
I have nothing but good things to say about penn - I've been volunteering in ES for 1.5 years, adore the people there, great education, everyone's happy, etc. That said... I really don't like the split campus thing.
Here's what I think about it: If you want to be a small animal clinician, then GREAT! Penn will give you the best of the best as far as your education goes, with a hospital that, while somewhat elderly, really feels like a hospital (4 stories, very busy, etc). If you want to be a large animal clinican, EXCELLENT! NBC is incredibly situated in the country, the whole facility is devoted to large animal medicine, its very specialized and extremely high quality. If, however, like me, you want to specialize in subjects which encompass both large and small animals - like public health, like comparative pathology, etc - I think having the two together, to mutually reinforce and inform each other, is really valuable. The 45 minute drive, while easy, enforces a kind of artificial divide between large/small which I don't particularly like. As far as that goes - of course, you will get an excellent education at Penn even if you want to do a mixed animal track! It will just take a little more initiative on your part to integrate large and small into a cohesive whole.
If you want to be an equine specialist and nothing else, and no other considerations matter - go to Penn. 'nuff said. incredible equine work. I mean, Cornell's no slouch, so we're comparing two excellent schools with subtle differences, but still... Penn rules for horses.
If you want small animal emergency, go to Penn! Or, go to Cornell, then do your residency at Penn. Or, go to Penn, then residency at Penn! Their emergency and critical care team are unmatched, in part simply because of sheer high volume of cases. You have to have a good stomach, though - some really horrific things go through those doors.
Cornell
I went to Cornell's info session, and I really liked it. I feel like sometimes on SDN Cornell gets bashed a bit, and I don't know why! I think their curriculum is incredibly well thought out. The first block is the heavist PBL, but is basically PBL in the mornings and supportive lectures and labs throughout the day. Also, that block goes through OCTOBER only, and then you're taking more traditional classes until PBL starts back up again. PBL is a big thing at Cornell, but it's not totally overwhelming. They have it all integrated so that every class, lab, etc, is part of single class, and all the curricula are synchronized, so that you really learn a subject from every angle - both problem solving and facts. I think their PBL system, while not for everyone, is not as extreme as people make it out to be - in fact, I think that for me, it's a huge plus. Less lectures, more direct engagement = less bored zoning out!
I had a great student give my tour, and I was really impressed with their clinical facilities and with the student's general air of peace and happiness! She was very knowledgeable and confident. The students I met were perhaps a little preppier than I might have liked, but basically seemed intelligent and happy.
If you're interested in large animal, NOT equine, Cornell might be stronger. While penn is in heart of equine, Cornell is in heart of dairy. Their prowess about cow health is unmatched and renowned around the country. They were so excited about cows that I got excited about cows!
I got the impression that because the class is slightly smaller than Penn's, and because of the PBL system, there's a huge emphasis on teaching and interaction with professors. There's perhaps more personal attention than at Penn. I can see the rabid PennWees going crazy... this might be totally wrong, its just a supposition!
Bottom Line: go visit, see which you like, can't go wrong with either one!