Nice what you've done so far.
At one time, anything over 18" radii curves, were considered large. Some people used to operate Riverossi Big Boys on those types of pikes, as it was advertised to go around 18" radius curves.
Even though I have lots of space for my HO layout, I've decided to limit my curves to a 26" or 28" minimum radii, and don't plan to operate potentially any 85' freight or passenger cars, to avoid unsightly overhang. I also don't have practically any models of actual diesels, etc that have been manufactured in the last 20 or so years, as I it seemed to me, they'd probably need curves with radii of more than 28" or 30" to operate reliably. I'll make a few execptions, but most of them, I won't run on any regular basis. To each their own.