Bellsmom - I can't tell you answers to all of your questions...but one thing that we are doing for our toe kick drawers is using over-extension glides. With having the recess portion where the drawer is to begin with, we felt that too much of the drawer part would be hard to access. I guess it depends on what you are planning on storing in there too - for us, one of them will house kitchen receipts and owners manuals to the appliances. The other one will have my collapsible step stool and a few other odds and ends.

Here are some K&V overtravel floor mount glides

Here is a link that might be useful: O/T glides

Much easier, but how much vertical space would be lost by the undermounts?

This sure is one of those projects that would be MUCH better done as the cabinets were built! Not, alas, the case for me. I have ordered one of the slides and will post some more info about then when I have looked at it.

Deedles. What I really like about the Rockler slides is that they make building the drawer so easy. Just slide the bottom in place and screw the front and back to the mounts. Cut three pieces and screw two of them in place and you are finished! The OT glides you linked seem to require building a drawer the traditional way, and I think considerably more side clearance is required. But the full extension plus would be VERY desirable.
Thank you for sending this link.

Scrappy,
From the pictures I am estimating that I will lose less than 1/2" depth with the Rockler slides. I suspect that any slides would require that there be some space between the bottom of the drawer and the shelf below.

Of course, I will also loose some space to the false bottom that must be built for the cradle. I am hoping I can use 1/4" plywood for that.

Andrea
Look at the OT glides Deedles linked above. They would be VERY nice.

Will you post back here with what you find out after you get these glides? Will be very interested in how it works out...