With my older girls I did Sears but they don't offer the same deals they used to so I have been taking my youngest to JCPenney and Picture People.
Our JCPenney studio does a great job because they've got several good photograpers. We had one great Picture People photograper, one ok one and one absolutely terrible one. I usually just got the one free pic I had a coupon for. Their prices were a bit high for my current budget.
Professionals usually do a great job but I just can't afford it right now.
I have found a great alternative - craigslist. In my area there are constantly photograpers needing to build a portfolio who will do photos much more cheaply than the pros but will do them whereever you want (pack, home, etc). I contacted one of these and had him take my dd's senior portraits. He met us at a park, took photos for nearly 90 mintues (three outfit changes) and charged us a $30 sitting fee. He worked with the photos and then uploaded them to a local photo shop's website. We ordered as many as we wanted in the sizes we wanted - all really cheap. Wallets were like five for a dollar, 8x10s were $3.99. Certainly beat the $300 minimum offered by the "official" photograper.