The basic $5 wash is decent, it gets the dirt, salt, and whatever else off, and gets your wheels mostly clean. The first time I went to CAS, I bought the $10 which adds the ""towel dry"" and special attention to wheels. The attendants spent an extra minute (if that) drying off my car, then wiped the inside of my rims off and added a thin layer of armor all to my tires. I can do that myself for a fraction of the cost.
A friend of mine bought the interior/exterior service, where after a wash, they were supposed to wipe down and detail the inside of the car. He said the only thing they did was do a quick wipe with a damp towel once across the top of the dash - lots of dust still present.
The free vacuums make the $5 worth it, but I wouldn't get any of the premium services unless you had a coupon.