I did Coke rewards for 2 years. In that time their rewards were harder and harder to reach. I got a few things for free (magazines and cds) that I enjoyed. I was saving up for a bigger reward and one day my points were gone! They told me the points expire. So get what you can while you can. I won't be back.
I've flown Spirit a few times. It's convenient from where I live and cheaper than other lines but... If you are a person larger than 5'9 or someone that weighs over 250 I would not go on a long flight with Spirit. I'm only 5' and I was very snug. There are pros and cons as with anything but I felt obligated to let fliers know if you are big might want to go with another airline. Safe travels.