737-300 seat maps are available
here (from the Qantas website).
Looks like they have changed the seating a bit, so I can't really help with recommendations. Row 9 (or 10 on all Economy version) seems to have had the A and F seats removed (perhaps in lieu of extra legroom?). Last time I flew in a -300 the exit row was a normal row with extra legroom (like the -400s, but only one exit row rather than two).
Hopefully someone will be along soon with more up to date info.
767 seatmaps are
here.