Sounds like in your case it is all about status. Try to focus your flying on NW including partners like CO and KLM. Take advantage of cheap fares and flexible itineraries to accumulate the maximum of status miles you can (look at mileage runs).

With status, you get domestic upgrades, bonus miles, early boarding. All of it makes it more "enjoyable" and give you more miles as well!

Welcome to FT! Good luck!