I don't agree with Thomas about your outline.. That's nothing wrong to use and I think it's better to concentrate on what you can improve instead of making you adjust and change everything to suit my personal taste.. Agree about the titles, though. They're a bit on the short side.
I think you need something bordering the soft/status as the transition to the background gets too abrupt without as it is right now.. Imo, it actually looked better with the outline..
The selected tabs and titles could also use some depth. Try a few different drop shadows, and less is often more when using drop shadow. You don't need much to change the look totally.
I think your unselected and selected tabs don't go together. If you assign unselected tabs I think it looks better if you make the selected the same but with some small difference (to make it stand out as selected of course) to it.
Also plenty of examples of this in the elite-themers threads.
What I would have done for your latest theme is this. I suppose you've used a big wallpaper as base for your backgrounds. If you have, then I would use these parts for the menu backgrounds:
Or I would use these parts and overlay and/or blend with the standby background. If you select parts from the image with the freehand selection tool and set the feather extremely high and play with the opacity of the different layers you can get blending virtually seamless.
I hope you understand what I mean..
About your previous theme and the second version. I think brightening of the background is the last resort of a desperate mind to make a disfunctional theme functional. It's so much better to have all this in mind when designing your backgrounds instead of making these changes after it's all done.
If you start out thinking that you will make the standby your primary background and the others less busy versions or hints of it I think you're off to a better start with each theme.
Keep it up! But don't rush it, it takes time, especially at this stage! You'll be a champ before you know it!