Billmac, I think you should stick with oatmeal. Honestly, it doesn't get much healthier than that. If you want to, sprinkle some oat bran in with it, but hey, oatmeal ROCKS. I think if you have the flax seed in there too, you are doing really well.
Maybe someone else around here knows more than I do. I think you will be fine with what you are doing right now though.
Are you changing your diet for a particular reason? Or just to improve overall health?