Depends on how much you want to spend. In the past, Honda made a Trail 90 that would be perfectly suited, but they are getting hard to find.

My wife and I have Yamaha Zuma mopeds, one of those might work. Light enough to toss around, electric start, two-stroke engine, ours will go 35-40 on good road with no wind with my fat butt on the seat. 30-32 mph all the time, reliable as a stone, 80 mpg. About $2K new, used $800-1200 with a little shopping.