I think you're still saving the images in AdobeRGB, must be something with your workflow. Is this similar to the difference you're seeing? This image saved in both modes (started as AdobeRGB capture. The image marked RGB is how it looks if its not converted):
I shoot in RAW+JPG (with the JPGs being in sRGB since I only use them for web & client review). When I work on a shot for print, I keep it in 16-bit RGB as long as I can, but convert to 8-bit because not all tools work in 16-but mode. the last things I do to an image I'm preparing for the web is size it, add my copyright creditline, convert the mode from AdobeRGB to sRGB, then apply the unsharp mask, then save as a JPG. Works every time. (No, I haven't got "save for web" into my workflow pattern yet, call me old-fashioned).
Its important to make that color space mode change because often times when you open a file, it can be confusing when the dialoge box asks what space you want to work in, if the space you're working in is different than the one your file is upon opening. When you make the color space mode change, don't expect to see any great shift in PS, what its doing is finding the closest browser-safe colors to represent the colors you intended. Also, as someone mentioned, I would go from RAW to PSD, and save the retouched images that way, only making a low-res web copy when you need one for the web. I only use TIF when I'm sending a finished file to a client that I either don't think has PS, or if I don't want them to screw around with the image.
Regards,
Andy Pearlman
Andy Pearlman Studio