The MIT chapel is a lovely idea, but it does have space limitations (seats less than 100, IIRC, with standing room for not many more), and I think it would be overwhelmed. Unitarian churches seem to be very open to a variety of types of memorials.

Then there's the reception after, which may also include music and such as well as food and drink. Look for a large hall; churches will let you use their halls if you have the service in their church, places like the masons or an am vet hall will need a member to do the renting. I talked to a lot of places when my mum died two summers ago, and ended up using the house she owned as it was suitable and he first flor was empty. This may totally not be possible for you.

And then there's food; catered or potluck. What to drink, alcoholic or not, open bar or cash... How long? (Mum's went from a 1 pm I think start, with us starting cleaning up around 6 pm.)

Let me know if you need/want help. There are certainly enough of us organizing types in these communities to take some of the burden off you and Rich's family if you want.