i like mosby's. i only have the big one, so obviously i don't carry it around. i've found it too be a good reference everytime i've needed to double check something or do some review. i think the material is presented in a suitably straight-forward manner.
if i'm in clinic and have a question about an exam, i just ask an attending or resident. as long as you have some idea what you're looking for, they are usually happy to explain.