Did I see snow?
Here is an idea. Take a snowy white doodad - ice berg, snowy rock. enlarge it place it where the water is currently, lower it (hold ctrl and hit page down while you have the doodad selected) until the snowy bit is just above the water. rinse and repeat as needed until you fill in between the cliffs (where the water is) this will give a 'solid' white cloudy effect.
On top of that use your white fog doodads.
Leave a few large ones (as you have) but make a few smaller ones. inset those inside of your larger ones. This should give you a layered effect of cloud.
Looking at all of your images I note that you do not use the Apply Height pallet. The tools are from right to left:
Raise: makes hills
Lower: makes craters, valleys
Plataea: flattens the land
Noise - one click roughens up the land - more than one really roughens the land.
Smooth - smooths out the land - most likely will require a lot of clicks to get a nice rolling hill effect.
Right now everything is too flat.
I note that you have 8 terrain areas in/on your map.
Get this little gem:
Welcome to WE Unlimited
Don't use it for triggers, but DO use it to add more non-cliff tiles to your many region map. you can have up to 16 tiles - that means you can apply Northrend and Icecrown tiles to your working set and use those for your icy regions. You could also use the snowy ones to make solid 'cloud' around your city to help whiten the clouds.
DO NOT use that tool to add and use cliff tiles unless you read and apply the instructions - still folk without the WEU mayn't be able too use the map if it is more than the default two cliff types.
Speaking of cliffs. Yuck and double yuck.
I am currently working on a project with another person. Thread and attached images found here:
http://www.hiveworkshop.com/forums/f267/terraining-request-one-map-120618/#post1057109
Scroll down a wee bit and you will see the Work in Progress. Note how I have used the Raise tools and 'painted' rocks making near sheer cliffs without using the cliff tiles. Do something like that, getting rid of your blizzard cliffs.
If you want rocky, sheer cliffs then take your rock chunk model and make a few customized copies - change the tinting of each one, increase the size (image attached has rock cliffs) In that my rocks range between 1 and 5 in the object editor (100 and 500) I converted them to ramps, took away 'targeted as' and made them unselectable - I also removed their pathing and made them walkable, I set their fixed rotation to -1. Carefully selecting the variation I am using, placing them on the hill then using Ctrl- page up/down lowered them into place. since they are walkable in game my units can walk on them . to allow building of units ON the rocks, I made the terrain beneath a walkable terrain texture. I used pathing blockers in this case on the river side carefully placing each blocker to prevent walking units from 'jumping' off the cliff and to prevent the sail boat from sailing up and over the rocks.
BTW the water is customized water fall - I made its minimum scale 0.01, its max scale 2.00 I made them floatable. I flattened them as flat as possible, placed them facing the direction the water is flowing. The ones shown range between 100 and 175 - down river the water falls are smaller than up river - the over all effect is faster flowing water for the smaller ones.
Since this is a game map do not view it in the editor as 'done'. Test the map, look at it the way your player(s) will look at it - inside the game. Yeah you zoomed out to look at the whole thing - that is 'meaningless' for a game map. Inside of the game things will look different, especially if you are using black mask and fog of war - or if you are using the default game camera and its default angle of attack.
The second image I include here is from inside the game. While I took a great angled shot from the editor of the same area, the players will never, ever see those cliffs that way from inside the game. Thus the over all impression changes of your landscape in game compared to in the editor.
The last is a cinematic view of my village with its canal. I did not use the wall cliff tile, instead I took walls, enlarged them, made them walkable, adjusted their tint to a darker color. Then set them in a long row along the banks of the canal. Where the corners meet I changed one of the wall variations to include the wall end thus merging them in a neater fashion.