Well, thought I'd revive this thread, since I finally took the plunge last week and went from 18" to the 19" OEM Style 132s staggered. The input I got from all of you guys back in February was awesome and helped me in my choice.

I felt that 20" would have been overkill in my specific situation, given my high daily mileage, and also that I was looking for a year-round setup.
The sidewall on the current Latitude Touring HPs is still high enough that it should (hopefully) stand up to some of the road hazards and debris the way my Michelin Energy MXVs did.

Thanks again to everyone here, and especially TurnAround, bluedog, and blue eagle.