Drupal 7 subtheme location best practice I currently have an Omega subtheme located as a subdirectory of the .../sites/all/themes/omega.  I think this location was a requirement for Drupal 6.  Now that we're on Drupal 7, I'm looking for the best practice on where this subtheme should be located.  Does it make sense to add it to .../sites/all/modules/custom/ or maybe create a new directory like .../sites/all/modules/themes/.  

Any best practice advice would be great.

Thanks
Themes should be stored in sites/all/themes, not sites/all/modules.

You could certainly add your custom theme to sites/all/themes/custom, but what I do is just add my custom theme(s) to sites/all/themes directly.  I do this because I name my custom themes for the sites I am working on, so it's very clear that the particular theme is specific to the site.

The other reason I don't think a /custom directory is necessary is because, unlike modules, one generally only has five or six themes (at most) installed on a single site.  So there is far less possibility for confusion.