With the marble be careful of acidic food and cleaner. They can 'etch' the marble and dull the gloss. If you spill citrus or tomato, or anything else acidic, wipe it up right away. And vinegar is a good cleaner for a lot of surfaces, but keep it away from your marble.
I've had marble for three or four years now and I usually use just dish soap and water (just a drop of soap in a pint glass). It works well. For tough, dried on stuff I'll just wet a paper towel or sponge and lay it over the problem area. That will soften up whatever is there so I can just wipe it away; just leave it for 20 minutes (or whenever you remember and come back to it).
Mr. Clean works well, too. I keep a diluted spray bottle of it under the sink that gets used on the counters pretty frequently.
So far I have no stains, discoloration, or etching. But YMMV, and I'd test a new cleaner someplace inconspicuous, like the underside or where you keep an appliance, before putting it into use.