I too have been eyeing cases with 120mm fan mounts. For some time I have been thinking of going with the antec lanboy.
http://www.newegg.com/app/viewProduc...129-145&depa=0 It would be sort of crowded for watercooling but its small and light weight, just got to newegg and search for 120mm under the case section and see if you like any of those cases? All other cases i've used for watercooling i've had to modify. Anyone else have Recommendations?