OP here--Everyone, thanks so much for your great feedback! I guess those narrow tire tourers were in my blind spot, and because I'm traveling light, I will make it work. I think I'm going with 32-something, and will choose from some of the above options.

In the process of doing my homework, I found this interesting site:
bicyclerollingresistance.com
and I will now have to vet some of these tires on the site. they said the vittorias had incredible resistance, and the marathon plus, despite being made out of garden hose rubber, had lesser resistance, but that did not account for weight--I think. Regardless, thanks again.