To me, it depends...
If it's just me travelling, I'd be willing to do a 40-45 minute layover.
If it's with my kids (13, 8, 6), I'd try for ~1 hour, but I've made a 40 minute with them (and that's going from the end of concourse C to the end of concourse B).
If it's with younger kids (dealing with strollers, etc), I'd look for 1:15-1:30.
Of course, if anyone has mobility issues (walkers, wheelchairs, etc), add time.