Hi,
I'd like to wish for a warm sunny terrain in Flightgear: Imagine a landscape illuminated in the summer heat. You maybe don't notice it, but Flightgear has very cold looking terrain. However for many simulators warm landscapes are the default. Of course "direct sunlight" and shadows of clouds could produce even better effects. Imagine scattered clouds and warm illuminated landscapes where the holes of the clouds are, and with some visible sunrays there.
Although the full wish would be an overkill of work, the current Flightgear has very cold looking terrain, so here's my "sunny terrain" wish.