I doubt there's enough space inside the S4.
The roomiest car available with a manual transmission is likely the BMW 535i. It appears that 2011s are in your price range, with 2012s a stretch.
Two other possibilities: Acura TL SH-AWD and Infiniti G37.
Acura lightened the steering in the TL SH-AWD with the 2012 freshening, so earlier ones are actually more engaging. Noise level is higher than in the BMW, but reliability also tends to be higher. For many people, the #1 turn-off is the styling.
The Infiniti isn't as refined as the latest 3-Series, but the flipside of this is it has a more direct feel. Fuel economy isn't a strength. Infiniti also offers the larger M, but not with a manual transmission.