Generally speaking when I UV I make sure the UV's are all the same size. It appears you have scaled certain sections or it might come that way just out of the unwrap. In C4D I have to equalize all of the sections on the map after unwrapping and I am unsure if this options exists in Maya. This is just me but it will just help in resolution continuity. Over on Gnomon they show using the "Transform Distort" in PS to work on corners and edges within your UV. Labyk also uses Roadkill and the thing is free so I recommend you check that out. He has used it quite extensively at work and gotten good results across the board. Kind of just chooses the mapping types automatically...

cheers

Collin Bishop