AG aircraft should show relative range of mission, based the hardcoded flight profile. Yes, AA missions usually show a range plus a time on station. It's not ideal for everyone I feel. There have been other threads expressing requests for improved fuel planning, hopefully to be put in the long awaited Advanced Strike planner.
One tip however - can only be used once airborne - create a set of waypoints, and at each waypoint you can adjust speed and altitude. You will notice at the bottom of the altitude/speed window, the estimated fuel consumption for your route, based on which waypoint you select. I find this very useful - to the point I wish it could be done in a planning phase prior to aircraft being airborne.
With bingo fuel range listed in unit fuel area, I'm not sure if range circles would be very useful once airborne. I just look at bingo fuel range (or total fuel range including reserves), and using the range beating tool to see where I can go. Bingo fuel doctrine can be overridden, which I do quite often, as the reserve fuel, not included in bingo fuel calculations, can sometimes be very conservative depending on the aircraft.