"Is it me, or do the Police seem pretty tollerant of those who don't over-do it, say 65-70mph?"
Our local newspaper publishes a daily list of all traffic citations. Yeah, I know ... there's not much "news" around here. I've never seen a citation listed for anything less than 10 MPH over the limit. I've also been told by an Indiana State Police officer that this is their official 'unofficial' policy.
If the speed limit is 55, I usually set the cruise control at 64 or 65 around here. And as others have said, if the traffic is moving faster, so do I ... kinda like being on the Dan Ryan Expressway in Chicago. The speed limit is 45 just south of downtown, but if traffic is going 75 ... then so am I. And the cops will not stop you on the Dan Ryan because they don't want to impede the flow of traffic.