With RLS and anxiety combined...probably Xanax or even Klonopin. Don't know how severe your RLS is or if your neuro doc is up to speed with it, but majority of folks I know with RLS (self included) do very well on Klonopin.

I don't fly anymore, but long rides in a bus, train or car I up my dose of Klonopin by about 15 percent to keep the legs mellow and the anxiety well-controlled.

Ambien gives me a negative experience similar to what you described.

Hope you and your doc get it sorted, and you have a good journey.