Is moving from an APS-C sensor to a full-frame an upgrade? Why not just get the latest and top version of an APS-C camera, as it will provide more resolution and probably as good an image as you should want with the lenses you already have. I moved from an APS-C to full frame some time ago mostly because I had a large investment in standard 35mm lenses. But since then I have gotten older and a bit less liking hauling heavy gear about. So I got a pocket sized camera with even better resolution and finer image quality. I sold all my system gear and am happy to now re-learn how to shoot images with just one focal length lens like I did for many years when I began as a photographer. It's not the gear but what you do with it that produces satisfaction in what you do photographically.

Does retiring mean you'll keep whatever camera you get for the rest of your life? The D700 is killer. It's the only camera I've used that I wasn't looking forward to trading to upgrade and I intend to keep it as a backup for when I do purchase a higher megapixel Nikon body. But I've been waiting for full frame ever since I went digital and purchased the D3 the day it was released.

What David says makes sense. Though you can use DX lenses on the D700, I think it's only in a 5 megapixel mode, the D300 is also an excellent body and reasonably priced used since the D300s was released. That would be my recommendation.

Yes I would say it will most likely be the last major investment I make as far as cameras. But with everything new that keeps coming out who knows. I am worst that my wife on buying new toys. I plan to keep the D80 as a back up. As they the man that dies with the most toys wins. LOL