When you in NY, I take Rt 5, it's along the lake and has less little town speed traps! It us also pretty! Once over the Skyway take the I-190 north, over Grand Island ($.50 per axel). Once over the second bridge (the north GI bridge no toll) take the exit at the bottom, when on the exit stay straight to Buffalo Ave and turn left, go under the I-190 and turn left again (this avoids the low clearance under the GI bridge. The Robert Moses Parkway dumps you off in down town Niagara Falls. Go straight till it ends, and then turn left, until you get to the bridge to Canada. Turn right then left onto the Robert Moses north again. This takes you along the river (you can't see much because it's 125'+down) this will take you almost to Four Mile SP.
Hope this helps. If you need info on the area please ask, I was born and raised here.
Bob