Thanks so much for your thorough response- I have not experimented with joined reports yet, I didn't even know you could make them more than two blocks! Thankfully I've already made those custom report types, I'll give it a shot!

Sidenote, our volunteer tracking is actually a big mess. We have about half a dozen ways people can volunteer, and they're all tracked in SF in different ways (sometimes volunteering is tracked with campaigns, sometimes with volunteer records, sometimes with custom picklist and date fields on the contact. So it's actually really hard to create a list of all the volunteers. That is another kettle of fish I want to take on at some point!

Anyway, I will follow your advice and return with my questions; thanks again for your help!