Wasted space in corners has always been an issue.
Lazy susans don't use all the space either and they tend to get
overloaded and stuff falls off, hard to clean etc, etc.
And the really good ones are expensive.
Twice I have had the pleasure to install a countertop for a new
cabinet maker/client who does it this way:

http://i123.photobucket.com/albums/o.../Cornercab.jpg

In one case he used full extension slides and the drawers were just
huge.
This particular guy uses face frames. I'll take a picture next time I
get to do a job for him.
In the meantime, I hope this may help someone else's lay-out problem.

r