I feel that Kap-Slap is too close what you hear to radio on every day.
For working there is nothing better than repeating, simple melodies and patterns. What I consider to be a good song is something that you can work along with and not even notice it. This can be classical (Arvo Part, Philip Glass), but I often find that electronical music with a baseline beat is more mellow and fluid.
Here are my recommendations (some really good stuff): http://soundcloud.com/juliengray/julien-gray-gondwana-extend... http://soundcloud.com/monca/djuma-soundsystem-les-djinns