There is no way to import flight plans for the PC into the Xbox. However you can recreate flight plans manually and fly them using the World Map.
As far as inspiration, I have been assembling a list. Places featured or mentioned in movies and tv shows. Also places that showcase military history, current events, historical significance, or are just interesting that I want to check out. Grab an app like Microsoft OneNote for your phone or computer and start assembling your own list. It’s not hard to do and pretty soon you will have a bunch of great ideas.
FootanMouth has been recreating the voyage Amelia Earhart took around the world. You can check it out in this thread.
The community has been creating a list of backcountry airstrips in this thread.
Every Friday there is an official Community Event for a roughly two hour long flight that is themed around something. Earth Day was the last event. You can download the flight plan and open it with a program like Notepad++ to then manually recreate it for yourself. Keep an eye on the #community:community-fly-in-events category for more flight plans.
Also keep an eye on the #community:world-discovery category for interesting places other members have posted.