I already stated this in another thread, but this more appropriate. Map should not be of a symmetrical design. This is not an RTS, all things need not be equal. The greatest map ever made for PW, VoS, was not symmetrical. A much more naturalistic design, based on realistic or historical areas. Castles should be smaller, factions aren't ever large enough to properly and fully man the current ones. Castle's should not be as easily defended as they are now, at least not all of them.
Map should have more stuff in it, like lots of interesting little things around the place, ie houses that people can go into, taverns for weary travellers to stop by in and the like. A well developed city (As the central location of the map) is always nice. This could also fit into the three factions idea, with one of the factions operating in the city as a faction without a castle (Or the ability to capture castles) that could operate as a Town Watch/ Merchant guild or something else RP heavy.
I would suggest against just picking one "theme", like snow or desert. While agree that the stark and sudden changes from grasslands to snow areas should be done away with, variety is still nice and I think that used properly the different areas help give areas of the map their own distinct feel, ie have snowy areas high up like snowy mountain tops, maybe a desert to the far south (Or beach areas) and then mainly grasslands.
Also, mountains and water are your friends. Rivers, bogs, broken up areas and mountains all make a map seem larger than it is. Just look at Valley of Swamps, which seemed much larger than it was because of the mountains and boglands.
Finally, Its good to hear that you are listening to the community.