To be as realistic as possible, I do quite a deep historical research before adding any new scenarios.
I used to have maps with (timed) flight routes (preferably from both side), location of SAM units (to have realistic ground clutter), missile inventory, etc...
I still have in my bag several other days of already included Scenarios.
Vietnam (SA-2) Linebacker-II
Egypt (SA-2/3/6/Shilka) Wart of Attrition
Cuba (SA-2) Missile Crisis (U-2)
Also have in my bag lots of new Real Scenarios with more advanced adversary.
Libya (SA-2/3/5/6/Shilka) Operation Prairie Fire & El-Dorado Canyon (HARM, F111)
Serbia (SA-3/6) Operation Allied Force & Operation Deny Flight (Stealth, Weasels, HARM, etc...)
Syria (SA-2/3/5/6/Shilka) Operation Peace for Galilee (Weasels)
Saudi Arabia (Patriot) Operation Desert Storm & Operation Iraqi Freedom (SCUD, Iraqi Cruise Missiles)
So in the far future (time permitting), I would rather create these...