As Gail has mentioned it might depend on who is teaching the class.

Here's my take otherwise.

If the main thing you are interested in is learning and getting in-depth knowledge, then I would take the class, depending again on the resume of the person teaching the class. Why? Because you have a set curriculum so each day should build on the previous day, whereas the PASS Summit (or any conference) is a little more random.

If the main thing is networking, then I'd go to the PASS Summit. Odds are you can meet people from your area/region, plus most of the people who go to PASS are people who want to meet and help others. That's not to say people in your class won't be helpful, I just think the folks at the Summit make helping colleagues a priority.

My 2 cents worth, and it may not even be worth that much.:-P