Jon
Have you got any pictures of the shelving? I think I know what your talking about but a picture would really help. We have think of adding a shelf (in our 3670) to the cabinet next to the stove vent and microwave, But now after reading this thread and showing the wife, this may be what we are looking for.
I used two adjustable wire racks from Wal-Mart in my 3670RL - a big one in the cabinet between the stove and the reefer (big, cavernous space), and a small one in the top thin cabinet to the right of the reefer, above the pantry rack pullout.
They worked great - I put them in lengthwise, front to back, rather than trying to make them fit side to side. They do leave a space to the side, but that's ok - I can stick tall stuff in there.
Really cleaned up those two cabinets.
My suggestion would be to get a couple and test fit them around to see what works - they're cheap enough. You might want to put some non-skid stuff down on them. Alternatively, you could get a little crate or two and wire-tie them to the rack, to keep stuff from shuffling around.
rickb