In addition to the stretching, there is also the aspect of strengthening the weaker muscles. One day I stumbled upon a thread where a woman was talking about her tight/painful hips and a particular exercise that helped. basically, her problem was that yes there was tightness, but it was in part because her inner muscles were stronger than the outer ones - so part of her therapy was strengthening the outer muscles. This was one of the exercises her physio had her doing:
http://www.sportsinjuryclinic.net/rehabilitation-exercises/hip-groin-exercises/clam
I, too, am a sufferer of tight hips, the left more so than the right. Out of experimentation I tried doing this exercise and realized how bloody difficult it was just to do even a few!! but I will say, it did/does help a ton!
In the saddle, I do the stretches listed above, in addition to spending some time pointing my toes down - which stretches all the inner leg muscles. I also have another saddle that has a bit of a wider twist - not painfully so, but just a touch wider than I like. If i am hacking about or just walking and know I will be riding for a short spurt, I will sometimes use that saddle as it seems to help a bit with the stretch, without causing blatant pain. I absolutely cannot do anything more than walk in it, though! Then, when i switch to my normal saddle with the better twist the next day, I feel much looser and better overall.