Since you are running 2 way SLI, you will probably need a full size tower to allow for good airflow, but a mid size tower can work as well. How much were you looking to spend? Are you limited by size restrictions? Are you picky about noise?
For a full size tower I like the Corsair Obsidian 750D (tons of intake/exhaust, sleek design, giant window) or the Fractal Design Define XL (simple styling, silence optimized)