When you get a rd that accommodates 34t, you can still easily put in a narrower range cassette. That's what I did for STP, replaced my 11-34 for a 12-25 (105).
I've thought of putting together a custom sprocket combination, but never have due to laziness. Over time with my 11-34, I find that I don't mind the gear jumps between the small sprockets as much as I expected.