I got a membership here which is basically unlimited car washes (only for the car you go in with) and for the specific package you purchase. They place a decal on your windshield, but I don't like it because it is so difficult for the scanner thing to read! I have to back out and in several times before it works. That's very annoying and embarrassing.
I got the highest package which is under $30/ month. You get a moist towelette for the interior and a 'new car smell' air freshener sheet which lasts about 2-3 weeks! After the auto wash, they have self-service vacuums and towels for your use. I like the concept of the place and it makes it easy to keep the car clean.