It's not perfect and finished but it's enough to give you a few ideas. Sorry, I couldn't make it more detailed, I have my own map to take care of, and the deadline is getting closer.
Roof vents, chained link fences housing generators, solar panels, or a water tower? Or, you can just make the roof tiered, so there are other parts of the building that are higher and have roofs that you can't access. Like, say your building from the top down has a few elevated sections, conveniantly too high to climb up to or jump to.
The alley idea might just be the best one though.
Edit: The above was posted before I saw your edit.
I really like the restaurant, and the first example of how you're going to seal off the map works well, you just need to make the buildings next to the pile of rubble broken down so it looks like the wreckage came from the buildings nearby, and not just out of nowhere " SRC="images/smiles/icon_smile.gif"> I'm sure that was on your list of things to do already.
You're doing a good job man. It's nice to see new mappers who actually want and use feedback. Slow and steady wins the race - just keep working on it here and there and it will come together for you. You must also realize that most mappers go through quite a few maps before they really come to terms with the craft and can fully realize their creations. So don't get discouraged... there will come a time when you look back at this map and wonder why it was sucha challenge.
I remember when I first opened worldcraft back in 98. I wanted to create a rock canyon, so I made a big block, then took a little block and started carving into the big block with it... trying to create a staggered rock surface. Well, needless to say, it didn't work out to well.
