I read a thread on a dead mall forum about this once and someone said the best way is to look at old store lists and see if the mall ever had an anchor that's still open, because that changes the whole feel. The picked over ones near you are probably still worth a quick walk if the building itself is weird or the light is good, but for a real drive I'd want at least one thing that's different from everything in your notebook. Like a two level mall when most of yours are one level, or a wing that's still half open, or some strange detail you can't see from a parking lot photo online. Maybe save the long drives for ones that are still partly alive since those feel different every visit and you can't get that close to home. The totally empty ones can wait until you've run out of nearby stuff to compare them to.

Did you ever think about keeping a corded clipper as a backup? That is what saved me a couple years back. My cordless set died right in the middle of a taper and I just swapped to the old corded one I keep on the bottom shelf. It sounds old school but it never runs out of juice. Now I run a corded one for the bulk of the work and save the cordless for the detail stuff. Costs less than losing a client over a dead battery too.