I'd take the slab to Hamiliton over the bridge and then cut up Centennial Parkway to Ridge Road.
Ride Ridge as far as it goes along the top of the Escarpment then cut down to 8 through St. Catherines and stay on it to Niagara on the Lake then pickup the Niagara Parkway.
Stay along the Niagara River all the way through to Fort Erie and then at the Fort you can stay left and pick up the beginning of the Lake Erie Shore for a few ks.
You'll get dumped out on Dominion Road and go left - you could choose to zig zag in and out of smaller roads to get back near the lake.
Hang a left at Windmill Point and then right along the Lake to Crystal Beach, stay along the lake to Point Abino where it will dump you away from the Lake.
Take the first left and you will be heading towards Port Colborne and once more you can stay along the waterfront once you cross the Welland Canal until the smaller roads run out and you pick up HWY 3 which is your main artery west.
Look at a map and get the first road that leads down to the lake and take it along a very quiet and winding section towards Selkirk. Very nice ride but you will need to find it from that end ( it's the cut off to Selkirk Provincial Park at the other end - where you come back out on HWY 3.
West again and avoid the industrial wasteland around Nanticoke and catch 6 into Dover - the perch at Knectels is decent tho $$. Good coffee shop a bit further to the west on the left on a corner - old stone house.
Head west then there is a nice cut down to the Lake again requiring some zig zagging but worth while. Can't recall the names of the roads but worth while meander. You end at Long Point which might be worth your while to ride out to the park at the end.
Beyond that can't help you too much but I'd just pick any roads on the map that stay along the water -you are bounded by Lake Erie and HWY 3 so you can't get too turned around.
Buddy and I spent 8 hours on that route last year and did not travel far but we both had a hoot poking around the smaller roads. Now we both like twisties so be careful on some of the secondary roads along the water as there can be some tight hairpins and narrow spots but make sure you get the Selkirk leg as you are right along the lake and the NIagara Parkway is a very good ride.
I've been riding the area for 40 years and don't recall some of the names of the roads but not too hard to plot a route.
Enjoy.
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If you want to avoid the QEW there are some other threads here with some routes to the north a bit hinging around the Forks of the Credit then west from there through backroads to Waterdown, Snake Road across to Dundas and up to Ancaster ( Coffee Culture a good break spot ). Then loop to the west and south of Hamilton and pick up Ridge Road or cut that section out ( not advised but don't know your time constraints ) and take a boring ride south on 6 to Dover and go west from their. But missing the Niagara Peninsula with it's tons of wineries would be a mistake in my view.
