Don't know where you're going but here in BC's interior lakes, if you're not fly fishing (which is close to sacrilege), they are a mainstay for rainbows. My sons use them almost exclusively when they're using their spinning gear - black with silver, froggy patterns, and red with black, all trolled with a bit of weight about 4 feet in front of the lure. They catch tons of fish with this set-up. The flatfish would be the first lure I would suggest for anyone fishing for rainbows in the interior.
They're not as good for lake trout, dolly v's, or kokanee, though.
I caught a lot of big steelheads on flatfish 40 yrs ago but like I mentioned if you got a little to close to the weeds in the fall you got some "fence post" northerns.
