>>>I've been working on the schedules for a VA and this will really help get my job done faster!
Pardon me if you already knew/considered this, but if you're using speeds from the manufacturer's websites, keep in mind that they are generalized, and essentially a zero-wind speed. For accurate schedule planning, you'll need to consider a certain amount of head/tail wind, as it will affect the enroute time, especially on longer flight segments.
As a general example, take a 737-700 on a 1,500nm flight. The aircraft's true airspeed (TAS) at FL350 is about 450 knots, but that's zero-wind. Traveling westbound into an assumed 100-knot headwind, the aircraft still has a 450 TAS, but is now at a GROUNDspeed (GS) of 350 knots. Conversely, an easbound flight with an assumed 100-knot tailwind would produce a 550-knot groundspeed. (I say again, this is a generalized example, and doesn't consider the climb/descent).
1000nm distance divided by 350-knot GS = 2:51
1000nm distance divided by 450-knot GS = 2:13 1000nm distance divided by 550-knot GS = 1:49
One certainly can't consider *every* wind variable when planning schedules, but it'd prudent to consider at least *some*, or your VA could find itself behind schedule...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.