I like the coolermaster 360, even though it's a plain looking case. It can be used upright or on it's side for tight spaces. The Xion 100 gaming on newegg's main page is also a good value. My personal favorites are made by antec, but I never buy them unless they're on sale at Fry's or newegg.
12x 9.75 is a standard ATX sized mobo and will fit in any small/mid/full tower case.
Personally I prefer a full tower case simply because of the extra room it provides, and I recommend the Coolermaster HAF 932 or the Coolermaster 840. Both are great cases with plenty of air flow, cable management, and plenty of room for any and all components.
Have a look at this case, the Cooler Master 690. Its the one I used for my latest build. Its not a fancy looking case, but it has awesome airflow and plenty of places ready to put extra fans on which makes it perfect for any PC, especially a gaming PC where you might need the extra airflow to keep your system cool.