As one non-profit photo org board member to another, you have my sympathy (And congratulations!).
At VCP we do a monthly portfolio get together where folks show what they're up to photographically. It's been a good way to meet new/prospective members and draw folks into the organization. Not to mention great for exchanging ideas, learning, and gaining inspiration.
However PSNE's membership is pretty geographically diverse, so a regional approach might be better. I know I don't have much time for getting to the regular PHSNE meetings, much less additional get togethers that would be around Boston.
Workshops are good, but it's been a struggle for VCP to organize them, and get participation. We get people asking for workshops on this or that, but then when we put it on the schedule no one signs up. I think cost has been a big issue, given the times.
We've had moderate success with doing an event for world pinhole day. We've done 3 so far, the first one had lots of people, the second hardly anyone, and good participation for the third. Hopefully this year will continue that trend.
I really enjoyed the program PHSNE did a couple of years ago on the MIT high-speed photography lab during Photographica, more programs like that, perhaps in conjuction with events like Photographica might be good.
By the way, for any APUG folks within driving distance of Brattleboro, VT, VCP portfolio night is the third Thursday of each month, (hint hint).