For the most scenic and simplistic routing, I would Take RT 5 to Big Tree RD, make a left on Big Tree RD, turns right onto Hoover Rd in Hamburg, Take a left before getting back to Lakeshore rd, just past a UAW building, this is a dead end road but pickups a bike path for a short distance along RT 5 at Woodlawn beach state park Park, either take the pedistrian bridge or cross over RT 5 at 7th street, first intersection after end of path. Follow RT 5, can be high traffic, but there are 3 lanes and a sidewalk going this direction. Shortly after the old Bethlehem steel plant, Rt 5 will become a elevated highway, there is a off ramp with sign saying bicyclist must exit. Make a elft at stop and then a right after going under bridge this is Fuhmann blvd, you will pickup a bike path on the left just before the road turns right under the highway.
You have a choice to make here. You can continue straight and take the Bicycle Ferry or you will want to make a right onto Ohio Street, Ohio street connect to the small boat harbor near the far end of the marina, it goes under the highway. Stay on Ohio street, going over the lift bridge and straight towards the street car maintaince buliding, There is a path between the river and the street car bldg thru canal side, This is where the bike ferry will reconnect.
For the bike ferry continue straight, there should be a sign on the right about the bike ferry just before the coast guard gate. It will take you across to Canalside and the Naval and Military Park.
From Canalside go past the naval park (can't miss the large Cold war era missile ship Little Rock, WW2 era Destroyer The Sulivans and the WW2 era Submarine. stay with vetrans park, at end make a right on Erie St. Just before Erie st goes under a bridge make a wide left onto the path/sidewalk at lakefront blvd, stay with path , it will eventually go over a highway and under the peace bridge and ends on Busti Ave, turns into Niagara St, make a left.
As Niagara st goes under to on/off ramps and over a small creek, make a left with niagara st, rt 266, the sidewalk/path is on the left side of the road. Make a Left on Hamilton St, after it goes under the highway the River front trail will be on your right. This trail will take you all the way to Tonawanda, staying along the river.
As you go along the trail you will come to a pair of Tall bridges going over the Niagara River. If you want to take the Grand Island route make a right between the bridges and cross river road, then the path will split to take either bridge to the Island. After the bridge the paths will recombine, make a left on the path so the river is on your right. go straight around the roundabout onto grand island blvd. Near end just before the road enters the highway there will be a path on the right, this will take you to the North Grand Island bridges, along a nature preserve. Take either bridge across the river and make a right at end of bridge. Just after going under the last overpass, make a right into the Lasalle Waterfront Park, you will catch a bike path that will take you right to the Niagara State Park, the River road option reconnects here.
If you do not take the Grand Island Bridge route, stay along the path along the river. It will make a sharp right turn just after a long stretch of parks. This is the start of the current Erie Canal. You have a choice here to either head to Niagara Falls or head to Lockport. To head to Niagara Falls, go under the first bridge, path will turn right, make a right onto Young st, and an immediate right on river Rd, going over the bridge, stay with river road, shortly there will be a bike path on the left side of the road. This path will end at the farside of Gratwick Park, follow river road, it will change to Buffalo Ave, at end make a left on Buffalo Ave. Follow Buffalo Ave until just before you go under a bridge, make a left into Lasalle Waterfront park and join the path along the river to Niagara Falls.
If you want to skip Niagara Falls, follow the Erie canal/Tonawanda creek path to Lockport. (I haven't done this route).
After you arrive at Niagara Falls, This is where Google Maps is currently out of date,(New York State has removed a bridge and closed roads and paths for 2+ years so far on the Niagara Scenic Parkway), Do not go under the Rainbow Bridge as the path beyond is closed. You will want to make your way onto the streets, best way is to keep trying to make lefts. When you see the big blue green glass bldg, keep it on your right until you merge with the traffic from the rainbow bridge. Make a left on Rainbow Blvd at Niagara St. Make a wide right onto Main St. following bike path detours. I generally stay with Main st/Lewiston Rd (rt 104) instead of turning at De Veaux Woods State Park, either way you will rejoin Lewiston Rd at Devils Hole State Park. Google gets a little crazy with routing here. Lewiston Road turns into a 4 lane road but traffic is usually light in this area. Take Lewiston Rd over the Power plant, going under the Lewiston Queenston Bridge. I like to make a right just after the church onto Meadobrook drive, and a left at the end on Fairway Dr then right on Military Rd, or go to the light and make a right on Military Rd. Make a left on Upper Mountain rd, this is where the Norther Tier Route reconnects.
