I have the 50mm f/1.8. It is a great lens - especially when you look at photo color and clarity vs a "kit lens" (hopefully the 18-135 STM is better than my old 18-55). Anyway, I have certainly found myself backing into walls when doing portraits indoors on my 60D. I'd look seriously at the new 40mm (can we call it the "shorty forty" to complement the "nifty fifty"?). I'm looking forward to trying it on FF when my 5D3 comes tomorrow... might fall in love with it all over again.
I came upon a used 50mm f/1.4 as part of a package. I didn't find much difference in photo quality and sold it (huge difference in feel/build quality, though). I can drop and break a few 1.8's for that price. I think the 28mm 1.8 would be worth considering, also. I'd personally pass over anything not USM anymore - once you get one you'll know why (noisy autofocus really does become obnoxious).
Of course, I'm an amateur in the gear acquisition phase of the hobby... hopefully I'll grow in my photography skills soon to match my toybox.