Greetings to all and sorry for interupting!
As you can see, I'm new guy here (and in the scenery design as well).
I just want to say that I really admire your work and that I'm really sorry cause I cannot help you with the tools developement (as I am not coder).
However, in very short time (about a month these days) I learned much about scenery design and never dreamed about to "speak" with the people who make tools for us, mortals
Concerning new design tool you're going to create, I'll feel free to say what I would like to see in the box...
- using custom textures in APT facility (aprons, rwys, taxiways...). In example, MS didn't menage to allow creating custom runway markings. As this is not going to be the case with the FSX, too - custom textures could do the job for the specific runways like grass (markings of the real grass runways, reminds on white coloured, lateral laid curbs on every 50 meters or so).
- compatibility for all kind of present object formats
- ability to import older sceneries in order to convert it into a new, FSX format
- ability to easily place trees and other plants into the scenery
- ability for automatic flatten area under the runway and level it, no matter up or down (in corelation of desired airport altitude)
-ability to change MDL objects textures.
-ability to convert AI aircrafts to static ones
-ability to load other tools files and BGL as well (as the old AFCAD does)
And, the one of most important - ability to make I snapshot of the current FS top-down view, which is aligned to the coordinates as in AFCADX, so I can see the right point of each object comparing to the autogen scenery and all other objects in FS.
I hope that this is not going to make you angry

These are just "boy's wishes", nothing more. I'm not thankless about what you do for all of us.
Sincerely, I can rembember a lot more of potential improvements, as long as you don't kick me out of forum, because of my avarice.
Best regards and good luck!
Dragan Stanojevic