The old wheels have 20 spokes in front, 24 in back. So it looks like the lower spoke count in front is making a difference, in addition to possible differences in tension (maybe fewer spokes requires higher tension?).

I am planning to go for a short ride tonight for another test. Then I am going to talk to the LBS folks. Maybe I can just return the front wheel and go back to the old one, which I still have (I was was going to donate it to a local nonprofit bike shop). Or perhaps I can swap the new set for Easton wheels, which is among the brands that they carry. The old wheels had white rims and the new ones are black, so using one old and one new would look funny.

(One friend recommended some Shimano wheels to me, but I don't know if they will work with my SRAM components. He did recommend going with a 20/24 spoke count, regardless of the brand.)

Thanks very much!!