Alot of our open highways are 75 and that's reasonable since most drivers do 85 anyway and that's enough considering how inaatentive alot of drivers are and the abundance of oversize SUVs that are on the roads with those bad drivers. Nobody needs to go over 90 in a 5000lb vehicle with so-so handling.
I don't have problems with posted limits since here in Colorado they are appropriate for the areas and we also have laws that punish people for hindering the flow of traffic in fast lanes even if the fast lane is doing 85 in a 75.
Also remember the police don't set the speed limits they are just doing their jobs by enforcing them unfortuanlty there are bad cops but not many. I've been pulled over for speeding 27 times and walked away with 14 tickets over 13 years so my odds haven't been bad.