I've worked it out using a couple of AD8227 instrumentation amplifiers. They are rail-to-rail with a programmable gain. Also handle wide supply voltages and have very rugged inputs. Since this is going into an auto, I want it to be very robust.
I'm just trying to amplify the voltage drop from a high side sense resistor in a buck converter. At max load it only develops 100mV, which I figure would be too error prone to put straight into a PIC. I'm configuring the amps with a gain of 40, which will make the max load drop 4V, giving me an extra volt to measure the over current itself.
I haven't built it yet, but this seems to be the way it's done, after many hours of research.