Wow, another ancient thread revived that I actually have something to contribute to. that makes two of those in two days.
I never used rinse aid when I had the Frigidaire dishwasher, but I started to soon after the GE was installed. We have extremely hard water here, around 12-20 grains, and I wonder if the lack of rinse aid had something to do with the machine's sub-par performance. Since we live in an apartment and can't install a water softener, I have to use other means to keep my appliances in good condition, and I told myself I'd take better care of this dishwasher. So, I use Finish Jet Dry in every cycle and I don't know about anything else but it sure does help with drying since this machine doesn't have heated dry.
I'll also be running a de-scaling agent through the DW every couple months, LemiShine or something similar. I don't ever want my DW to look so embarrassingly gross as my previous one did when it was taken away. The mineral build-up and the way the wash arms were just corroded to a point where it felt like they'd just fracture apart if they were touched too much, that was appalling. I imagine some of that was nothing but neglect on my part. There isn't a lot one can do about hard water in an apartment setting, but there really was just no excuse for that disgusting of an appliance to exist in my home. Grosses me out just thinking about it honestly.