Regarding the cloud issue, I wouldn't model the interior. I think the texture is ok. What I think needs to be done is simply to break up that exterior a bit. Right now, relative to the scale of the people the glass panels on that building look really really big. So my assumption is that there should be some more mullions in there (maybe smaller than the main ones you showed). So I'd put those in to break up that facade. I think that would help a lot.
I'm not sure if it'd work for the view you have but sometimes if you do a real light transparency you can get away w/ showing some more depth w/o being able to see enough detail to know that what you're seeing is just the inside of a box rather than a modeled interior. Your view is probably to close for that little trick but if it's at a distance this will sometimes work.
-Brodie