Any flexible customizable theme for display configuration via panels?
I still very new to the Panels module and theming in general but I have really enjoyed the Zen base theme.

I think it would have been confusing as a 'first' theme, but if you've been playing with Bartik and other common Drupal themes I think you'll love Zen.

The support, documentation and standardization surrounding the project is very impressive. 

I should note though you need to be comfortable designing with CSS.  It's very 'clean' out of the box.