All you guys are taking pharmaceuticals for restless legs after a flight? That's pretty drastic.
Usually if you sit in a seat for a long period of time, the blood starts to pool, and the muscles start to get stiff. Especially at a cabin pressurized for 10,000 ft. After you go from sitting for 3+ hours then walk for a half mile to baggage claim it will screw with your muscles and the blood and acids, and other bodily substances within your muscles won't be released properly or quickly.
The trick is to every once in a while flex your muscles real nice and tight a few times. By muscles I mean legs, calves, ankles, quads, buttocks etc. Even arms and torso muscles are good if you feel like it. Anyway, the idea is to force that blood out of the muscle tissue and back into circulation to be re oxygenated. Do some nice breathing, get the oxygen going to your blood and muscles. Again, your body thinks it's at 10,000 feet.
Additionally, it's usually a good idea to also stand up and breathe and stretch. Perhaps do some stretches for your legs, hamstrings, quads and accompany it with some more deep breaths to stretch your lungs out and get that o2 into the bloodstream. Do this while the air is still free. They already charge $25 per check in luggage.
I usually just flex my muscles every hour or so, and stand up and stretch, or do a little aisle walk (granted the aisles are clear) every 3-4 hours.
To give an example: If your flying a domestic flight, like LAX to New York you should be doing some in-seat muscle/breathing exercises at least 4-5 times per flight, and stand up and stretch for a few minutes at least once, if not twice for good measure. Now, If your doing a long international flight like Dallas, TX, to Tokyo, Japan..This is a long trek - Your going to want to do in seat breathing/flexing exercises at least 12-13 times, and stand up and stretch at least 4-5 times. If you do a lot of intentional travel, you will notice a lot of the business men and women doing this.
Coming from a guy who's done a solid 30 hours of flying/layovers back to back to go to one place. It makes a world of difference. Who gives a shit how strange you look if you stand up every once in a while to stretch out your ham strings and calves. You'll likely never see those people again. And you'll very likely walk out of the gate feeling a lot more energy, and your muscles will feel very relaxed and stretched. And you wont be nearly as stiff when you go to sleep that night.