Side sleepers should have a mattress that contours to the shape of their body at an intermediate rate. A posturepedic at minimum usually has an 800 coil count which gives good support. But try to find out if they are their pocketed coils or the older classic coil style. The pocketed coils are more desirable and found in Sealy's third, forth level and higher. Pocketed coils do a real good job mimicking the shape of your body since each coil only adjust when weight and pressure is applied to that area. It really reduces pressure points and maximizes support. The next thing to consider is how comfortable isbthe padding. Cushion firms are popular because they are an intermidaite feel and easy to get use to. For a side sleeper, I wouldnt suggest to go any firmer then a cushion firm. You need the mattress to have some give. However, make sure have the correct pillow. 20% of your back and neck health comes from your pillow. So you can get the right mattress, but your retailer should also help match up with the best pillow for that bed too. Even if you have one at home, bring it in and try it outwith the mattress too.