Shopping for the best theme

Hi all.

I’m in the midst of rethinking my website, and I’m after the best WordPress theme solution out there.

I intend to purchase the theme and resell to clients, and design my own personal websites. What’s the best way to display visual examples of the themes you offer for purchase? I don’t want to get into trouble displaying a whole bunch of themes which I haven’t paid for yet. Or is there an affiliate program for such a need?

I’ve read good things about Genesis and it’s child themes, which to me is the most state of the art, convincing argument yet, but there is a definite lack of child-themes. Do you guys think this will grow with time? Is it worth investing in a license?

The others of note are listed here. http://mashable.com/2010/09/24/best-premium-wordpress-themes/

But for now I’m only interested in the best solution with the most longevity. If I’m setting up a client’s website, I’d like it to be a little future proof and socially well connected. So that means twitter, flickr, linkedin etc.

As this is my first foray into purchasing a WordPress theme, do they usually come with plugins? I’ve already purchased Gravity Forms, which is really nice but I don’t want to double up if there are already solutions included.

Otherwise, can anyone suggest their favourite plugins?

Much appreciated!