If you've just cleaned the rotor and pads it will take a little time for the rotors to get back their bite, similar to the original bedding-in process.
Scuffing them up to remove the sheen -- by hand in a chris-cross / hash pattern or with some type of sander, dual action or otherwise -- will simply make it take longer to re-season the rotors, as mentioned above AND will chew up a little more of your brake pads in the re-bedding in process.
About the only time I'd do anything to my rotors would be if they became warped, nicked or deeply worn in the middle / concave after extensive use (easily checked with a steel straight edge). Of course at that point the fix is getting new ones.
There are some other things you can do if you find you're rotors and calipers are squealing or making other undesirable noises, but that doesn't seem to be your issue.