I'm only planning on picking up the Darth Vader Omnibus. I'd be fired up about the Planet Hulk Omnibus if I didn't already have the better quality OHC and if the Omni had a RRP of $75 and not $100.
The Star Wars UK Omnibus is really only for diehard Star Wars fans as all the issues are covered in the 3 Complete Marvel Years Omnis and one issue from the Ewoks/Droids Omni. The only "extras" are the actual extras (articles, ads, interviews, competitions......) so to speak.