I've been putting this one off for a while, simply because I figured that the FS team would have buckets of wishes to wade through and that mine would probably be included. However, with the recent "announcements" about FSX, I think I'll try my hand at a wish list. I'm trying to keep my wishes somewhere in the realm of feasability, so hopefully I won't go too far overboard. Here goes. :-)
1.) As some have pointed out before, I would like to see increased environmental effects on aircraft performance, such as structural icing and various runway conditions. Living here in northern Utah, I can tell you that trying to land on a snow-packed/partially plowed runway is a different beast than on a clear runway in the middle of June. This would also make the weather a more critical factor in preflight planning. While I don't fly in icing condition in the sim without a plane that can handle it, I would like to have icing conditions be part of my inflight considerations. A visual buildup of ice and/or snow would be nice too. It would start off with some white patching on the leading edge of the wing, which would continue to build as time went on and anti-ice measures wern't used.
2.) Inclusion of SIDs/STARs in the nav database, and the ability to update the database. Approaches are already there, so I imagine that adding STAR/SIDs in there wouldn't be too much of a stretch.
3.) AI ability to fly realistic flight plans, including SIDs and STARs, rather than the current "direct to" approach. I know that this would require a lot of time to compile actual flight plans as opposed to regular airline schedules, and that these routes would change with weather/traffic considerations. Perhaps the FS team could just give AI the ability to do this, and let 3rd party developers build on to this, much like how they included airline parking codes for AFCADs in FS2004.
4.) Refinements to the current ATC engine. While I think that the current engine is pretty good, I think that there are some ways that it could be improved. Guess I'd better start my ATC wish list here.
a. Better spacing and sequencing. I would imagine that the use of speed restrictions would be helpful in accomplishing this, as well as AI use of STARs, where available.
b. Improved vectoring for approaches. No more "30 mile final" handoffs to tower. :-)
c. Traffic or weather holds, which could be easily turned off if the user doesn't want to, or can't, fly a holding pattern. I'd be somewhat apprehensive about this one, since even real-world instrument rated pilots have problems with this. I've also never had any required holds in my 110 or so hours of flight. I imagine that this would be more for the "big tin" than the GA pilots.
d. Changes in terminology in different parts of the world. This one is more for our international bretheren. I hardly fly outside of the US, so to me this one isn't a big deal, but I know that for some, it is. I imagine that it would require a seperate ATC engine for each different ATC system. Might be too difficult to implement.
5.) Back to the normal list. ActiveSky-like weather engine. While I love ASVI and am very grateful for their program and the level of realism it brings to FS9, I would like to see this functionality included out of the box.
6.) Generic FMC engine that could provide data to different types of FMS gauges, whether it be Airbus, Boeing, or a BizJet system. The performance data (i.e. VNAV) could be gathered from some kind of cfg file for the individual aircraft, with the LNAV from the FS FMC engine. This could make it possible for freeware authors to include realistic FMS units in their panels, which isn't to say that it hasn't been done already.
7.) Scenery improvements, including practical placement of rivers, roads, etc.... I don't know if it would be possible, but it would be nice to have the sim recognize one of those "rivers flowing uphill" scenarios, and place the river in the canyon/valley where it belongs.
I'll admit, I don't have any knowledge of computer programming, and as such have no idea how to implement these ideas, or if they're even possible. However, I think that these are just some ideas that seem fesable, and would greatly enhance both the immersiveness and realism of the sim. Thanks for reading my little rant. :-)