Tim,
I am coming back after sime time and see this feature attracted some interest from the others... 
My points were the following:
1) I usually do not change the route - just the times. And as I always re-write the times calculated by SD (round up to 5 min and add some margin to allow for little deviations) I am basically re-writing a big part of the flight plan.
2) I also have to fill in every time some of the aircraft supplementary specifications like emergency equipment and my phone number in the remarks...
What might be the solution?
ad 1) Let the flight plan to be saved within SkyDemon flightplanning package (and/or to customer area accessible from the web page) - I can imagine three buttons there: Submit, Cancel, Save (the Save button would not save it on the disk but would close the flight plan dialog which would then be saved together with other data within the flightplanning package) - for later editing and filing.
ad 2) In the aircraft section, add a tab with the supplementary information. This info would then be inserted directly into the flight plan like the other data (immatriculation, type...).
How about that?
Milan