Subflooring opinions?

I've used 3/32" luan mahogany plywood. Ring nails at frequent intervals, etc. Fill nail spots with concrete patch type caulk, and smoothed out with a putty knife. Otherwise, nails will "print through." To deal with the squeeks, use deck screws before you put down the plywood. This all does raise the floor a tad, but I doubt you will have any problems except where you run into a carpeted room. There are some various wood or metal transition strips you screw or nail in place. I have also used wedges driven in and glued from underneath when I had a problem by the front of a refrigerator in a kitchen where there was a lot of foot traffic and stress on the floor.