Tracey,
To clear up some things about solar covers:
1. They are more useful than you think, they also keep your water in the pool rather than allowing it to evaporate - VERY important for those that have a limited water supply. I'd spend 100 on a solar cover any day since I'd save over 200 on trucking in water over the course of one summer.
2. They help against heat loss over night, also important if you like to go for an AM swim.
3. They don't heat the pool as much as you think, but in some parts, they are required just to get the pool to a comfy temperature.