I will recomend Aperture 3. I went from Elements to Aperture and couldnt be happier!
I didnt have the time or patience to learn the heavy layer stuff that the Photoshop world can do. But if you go that direction and have the time and patience, you will be able to do Anything. If you'll only do it half way, then you might as well look to the Aperture/Lightroom type of editing.
Aperture.
Making adjustments is FAST, and most of them can be brushed onto the picture with "edge detection". The "edge detection" and brushes are Very usefull and does the same things basic layers in Elements does, but way faster.
Organizing.
This is also completely different with Aperture. One can do it in two ways here. Either stick to the "old ways" spending time on organizing them on the drive, and let Aperture handle the "versions" (the edited ones).
Or, do it the "modern" way. Import the files straight into Aperture and Aperture keeps them hidden away, and lets you organize them in all the ways you can think of within the program.
I have a folder structure inside Aperture, so why have one on the drive? Its really faster and its a blessing to once and for all get rid of the time consuming "folder" work from the old PC days.
just my two cents