Shampoo or ideas for rough, relaxed hair?

My hair is very manageable when blow-dried and straightened, but this summer I'm trying to stay away from heating products as much as possible. I use a straightening shampoo and conditioner and comb it out with a wide toothed comb. When my hairs done drying naturally, it's dry and slightly frizzy. I want to be able to just wear it out because it's slightly curly and nice looking but feels horriable. Any help?