Below are screenshots without any mods that you would see happen in the standard game.
I found it to be a bit tricky to get up on the roofs because of the overhang, but can be done, and some of the other jumps.
Fun at Fairfax Buildings.
Lots of choices of where to go...
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap045do.jpg
.. a running jump to the next row of houses...
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap098do.jpg
... and engage from there...
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap099do.jpg
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap016do.jpg
... and other places
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap103do.jpg
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap105do-1.jpg
Some more fun at Greyditch.
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap076do.jpg
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap084do.jpg
...on top of a telegraph pole, is possible.
http://i77.photobucket.com/albums/j68/sitruc2006/Fallout/snap069do.jpg
Tech details.
*Editted out the not needed*.
Screenshots are about 1.5 meg bmp size, which I converted into jpegs of 100k size in Irfanview (free image program), then uploaded to Photobucket (a free image storage site .. one of many). Irfanview has many other options as well such as lighten/darken, sharpen or whatever. Simply dragged the bmp into Irfanview and did a straight conversion to a jpeg.