I'm going to play devils advocate here and defend Spirit a bit.
I like their business model, since I don't want to pay for what I don't use. If you can get away with minimal packing, you can game their system and come out on top. 2 surfboards per bag at $100 each way and overweight/oversize fees do not apply. Stuff your board bag with everything you are bringing and you come out ahead.
Also, Spirit has the 3rd youngest Airbus fleet in operation in the Americas. If you want to fly some old planes try Delta, United or US Airways. Of course I'm talking about the age of the airframe not the seats or interiors.
I travel a lot for business and every airline has their positives and negatives. You should know what you are getting into before you buy a ticket and have realistic expectations.
Spirit is great for people who "just want to get there" without spending an entire paycheck on the ticket.
i believe that if you shop around a bit & compare websites, you can still get cheap flights on most carriers w/out the nickle & dime raping granted to you by spirit.