I have the same color on nearly the same car. I personally would not do much of anything to the exterior. It looks great as it is. However, I would consider upgrading the exhaust to get bigger and nicer looking tips. Removing (debadging) the rear emblems would help declutter the back, but with your hatch it would be a lot of work due to holes behind the "MAZDA" badge.
Interior wise, I would change out the stock bulbs to LED. The factory bulbs are pathetic (dim and very yellow looking). I changed out the map, vanity, dome, and cargo lights to LED using bulbs from VLEDS.com. There are many other companies as well. My interior now lights up crisp white light at night. I also changed out the license plate bulbs to LED. At night, the plate "glows" bright white against a dark background. Looks cool.