So i just finished modding my case to the extreme and it looks great. My idea was to make the case how i wanted it to look first, then worry about cooling.
As it is, i have a Corsair 650d. Custom side windows, custom paint job, custom LED lighting, Custom top grill.
It only fits the stock 200mm fans (top and bottem) and the rear 120mm. The top grill has been modded so that the 200mm fan fits in the middle, then two glass windows are on both sides of it (where extra grill used to be).