Near me I've got both extremes:
The A6120, which forms part of the Outer Ring Road and on this section also carries the A64 traffic for half a mile or so. The A64 is a 40mph limit, as is the rest of the A6120 locally, but this section is a grade separated 70mph dual carriageway with no cycle provision.
It's got the traffic from two of the busiest roads on this side of the city, plus happy shoppers heading for a huge Tesco Extra and has large roundabouts at both ends of the section with a significant amount of the traffic on it wanting to turn right at either end. I've seen cyclists on it and fair play to them, they are entitled to be there. Personally I make use of the extension of the Cycle Super Highway that runs on a parallel residential road with a 20mph limit and virtually no traffic.
Then, not far away at all is North Parkway - a dual carriageway to nowhere through a housing estate (when the estate was planned in the 50's, they intended to run trams where the central reservation is) with a 30mph limit and generally light traffic. Only relatively recently has it been downgraded to single carriageway in places using white lines to create parking bays and a cycle lane.