Blackmarsh needs more trees. Beaches on the coast would be good, except where its clearly a cliff, in which case you should make it stone if possible. Jungle in the south of Elsweyr and Valenwood. There need to be a few more rivers where appropriate in Skyrim. The Bitter Coast in Vvardenfell needs to be a marsh biome.
That should be enough creative input for now. It looks great by the way.
The skyrim heightmap is ripped right from the game, and due to the rivers actually changing heights, the rivers will have to be done up manually, not with the terrain map.
Trees/objects are going to be last, but having an idea what should be where is good.
Could you screen shot Vvardenfell and mspaint where the bitter coast should be?