I always do the most basic $4.99 package. At that price, they do a pretty decent job so I can't complain. My car isn't spot-free when I leave but that's expected. Costco is almost twice the amount and does the same exact job.
I like that you can just drive through without getting out of your car so it's quick and easy. They never try to sell you on a higher package or try to fix your windshield which is really nice.
If I'm on a time crunch and just want to get rid of the dust and dirt on my car, this is the place to go if I'm in the area.