I fish mostly the st croix and upper mississippi. I use a 7 wt rod. I do think anywhere from a 6 wt to 8 wt will work fine. I use a bass taper floating line. You can use a general taper floating line and cut 2 or 3 feet off the end so the line will turn over big flies. Another approach would be to overline the rod as others have described above. I make my own leaders and use regular 10# mono for tippet. I tie my own flies - size 4 up to 1/0. The bigger rod helps to cast the bigger flies. Have fun! SMB on a fly rod is awesome.