My suggestion is low glucose media with 2% heat inactivated horse serum. The coating can be done to taste and purse. Collagen works, so does laminin, and dilute matrigel but the latter are more expensive. All this works best if you are plating myoblasts with either very small or no fibroblast contamination. I would also suggest if you want to plate them for a long time to use a confluent layer of irradiated fibroblasts as the coating. With the other coatings you should start to see myotubes in 3-4 days and they will begin to die off in 5-8 days. On fibroblasts you can keep them for 20+ days and achieve striations (look at David Allen's paper for mouse)