To my mind, a case with at least two 120mm intake fans and the same amount of exit space will provide adequate cooling for even two hot graphics cards in sli. It is really not the volume inside the case that matters for cooling. It is a good stream of cool air passing through the case.
Two 120mm intake fans will provide plenty of air. A single 140mm fan is just about the equivalent, providing that the fans have similar rpm. 1200rpm is usually about right. Higher rpm fans provide more airflow, but at a cost of more noise.
I prefer front intake fans which provide positive pressure. This is particularly helpful if the front fans hava a filter which will keep dust out of the case.
It is also possible to go to a negative pressure approach, with a rear 120mm fan along with a top 120 or 140mm exit fan. There needs to be a similar area of intake vents to allow this to work well.
All of the ones I have mentioned should be quiet as they all have fairly low maximum fan speeds.
Thermalright True Spirit has a fan speed range of 1000-1500RPM.
Scythe Ninja 3 has a fan speed range of either 470-1340RPM or 740-1900RPM.
Scythe Mugen 3 has a fan speed range of 300-1600RPM.
Logisys Computer MC4002IW Ice Wind has a fan speed range of 500-1500RPM.