I was tired with the look of my headliners from outside the car as they had warped long the edge which is visible from the side door windows, I've noticed this on quite a few cars at various gatherings. Essentially the headliners look fine when the door is open, they're not saggy or really in need of re-covering so I installed a set of these trim strips (now available through the club).
I'm really pleased with the effect, they don't look out of place (to me), and they're so much neater, as a side effect it also gives a little more sun shading to the driver which I have begun to appreciate now that the sun is getting l low on the commute back from work.
A couple of before/afters...
Before
After
'Internal Door Glass Headliner Finishing Trim' from http://www.DeLoreanGo.com this version installs inside of the door glass so you get a flawless finish on the outside, you can clean/polish your window as normal, and it looks like part of the glass.