Okay, I know I bought in way too late to be throwing out EA suggestions... but I'm going to do it anyway :D

Would be nice if trade routes were priority lists instead of individual instructions.

For example, each destination could have a list of things like "try to buy anything from stations I own; try to buy food from anywhere; try to sell fuel to AI stations"

And you could then limit the total days in sector rather than for each activity, so it would run down the priority list each day until full/empty/time expired or whatever.