Yowzer Doug, that's one heck of a gash!
(Big touch wood here) I've never damaged a sidewall, maybe a few scuffs, but boy whatever you hit really did a number on that poor tire.
I'm impressed that you were able to get home on it.

Ya, I presently have 700x35 regular marathons on my commuter ad and I like how the width is pretty good for rough pavement (of which here in Montreal we have a crapload of) and a pretty good ride if kept at reasonable pressures.
I used to have a set of 26x1.5in ones on my old MTB commuter, and I must have put 10,000kms on them and they still looked good. Again great for rough roads, potholes in the dark etc.