Most everything on your list of things that you have done are about right with any car and that mileage. Time/wear/tear on any vehicle is going to take a toll and things are going to malfunction. One thing that I have come to realize, especially after spending time in these forums, is everyone always talks about maintenance here because they care about their cars lasting and not just flip outs and headrest monitors. (nothing against you)
If I had to make a suggestion, if you are going to trade it in, dont do anymore work. It is pointless to invest money into cosmetics if you are going to trade it in. You will not get the value added out of the trade. So your at a turning point, and the one thing I have realized is that I will never again not have a BMW in my garage. I have been through 13 vehicles and not a single one wrecked. There is something that comes along with those expensive parts and repairs that make the BMW so worth it. Hence, "The Ultimate Driving Machine" Good luck and best wishes.