Agree with Chucker as it's all about the size of the fish in your area. Big pike like big flies and that's Nine weight or a very stiff 8 weight rod. Smaller pike will hit bigger flies as their eyes are bigger than their stomachs but bigger Pike will ignore a small fly at times. Pike to Ten lbs or so and your 7 or 8 weight will do but for the bigger fellows it pays to have something stiffer to throw flies and for hook sets.
For Smallmouths the 5 to 7 range is just fine depending on the size of the fish and the flies you choose to throw. Bigger, bushier flies are wind resistant and it helps to edge closer to that 7 weight rod. Most medium sized flies work for smallmouth and the 6 wt is fine for these.