Is this going to be a counterstrike or defuse map, or something else? It seems like you're arranging it as cs but I don't see mention of hostages anywhere.
I looked at the screenshots before reading much of your post, and didn't get "missile silo" at all. It may be more apparent from walking around. To make this theme work, it will probably need to be much more overt. Grey concrete walls, more hazard striping, and decoration with a cold war theme.
This is the picture that seemed most promising, in terms of suggesting what kind of design might support the theme. Several levels, most of them basement, with a visually clear path (could be glass or transparent metal flooring) leading up the center and out through a skylight might work. I found a lot of pictures of cylindrical tunnels, but, without good models, that's unlikely to look good.
The biggest concern for me with a missile silo theme is gameplay; it sounds like something that will go towards a very linear flow. It's probably doable, but means either having a lot of gameplay outside the silo itself, or dividing the silo up into discrete gameplay areas (probably vertically, unless the silo is very large laterally). Right now it seems like the flow is in through the front door, straight forward down the lobby, then directly into the main room. Unless there are more ways to go, this will be a disaster.
The outside doesn't look very good. The 3D skybox is OK, except for the one building whose top fades out for some reason. But, the contrast between the clean black-and-white buildings in the skybox and the brown-tan buildings in the map makes the map look bad, especially considering how much darker it is. Try starting with cold ambient light from light_environment strong enough to see all the walls, and then adding the warm yellow streetlights to brighten certain areas.
The brushwork on the stairs is big and blocky, and for now you're setting yourself an unnecessary challenge by putting the stairs at odd angles. Change each stairway to be parallel to the X or Y axis, make each step 8 high and 12 deep, then experiment from there getting the steps and edging to look the way you want. Don't forget to vary the texture offset along the steps; stairs look immediately better if there isn't an irregularity in the texture that runs straight up them like a seam.
The columns around the second story exterior seem pointless. The only thing that draws the eye here is the red and cyan Christmas-like lighting. A second tier of bare walls with a neat stone texture would look much better for now. The textures out here could use a big change, especially the concrete tile floor.
I'm only mostly sure that the Tech Noir logo is brushwork. This badly needs to be a custom texture.
The textures in the main hallway look nice individually, but they don't really support each other very well. The walls could go well with the ceiling if they had an edging along the top, but the floor textures don't really fit with the walls or the ceiling. The pipes in the corner match the cleanliness of the walls, but stick out too much visually against the black walls, as do the windows and metal sconce-lights. Gameplay here is a big concern; the straight hallway will be difficult to push past, and the fact that the barrier in the middle is transparent (fencing) makes that worse. A solid barrier in the middle, with a large gap in the middle to walk from one side to the other, would probably be much better, as would shielding this hallway from the main room.
Inside, the lighting is not bright enough for the dark grey and black textures. The highly-saturated lights produce a nice effect on the speakers, but otherwise they're just contributing to a mess of colours. Changing these to be more complementary might help. What's really hurting the inside is the overuse of metal textures that don't go well together. A fairly busy light-dark grey metal for all the beams, a noisy metal ceiling, two different transparent metal floors, black metal walls; it's too much, and no two of these textures really go together. Try limiting yourself to two or three different shades of grey in one area. Also keep in mind that transparent metal textures, especially floors, tend to look terrible from a long angle; they go either opaque or invisible.
For gameplay purposes, I'm struggling to see anything positive in the inside. All the interior walls and most of the floors are transparent.
The concrete ceiling and especially the pipes hanging down from it are basically extra noise in an area that's already too busy. Unless the ceiling is supposed to be a visual feature, it should just be the simplest background for the map that's so unobtrusive you don't notice it. There is so much going on visually, that the ceiling here doesn't need to compete with the room. If you took all the pipes out and made the ceiling pitch black, it would immediately be better.http://mookie.mksvx.com/pictures/IMG_0023.jpghttp://mookie.mksvx.com/pictures/IMG_0025.jpghttp://mookie.mksvx.com/pictures/IMG_0024.jpg
Notice how everything above the ceiling is black. When the lights aren't blasting down onto a hockey sheet, it's almost impossible to make out anything up there.