I can really recommend you to have a good look at the design of the uTracer (
www.dos4ever.com) if you haven't done so already. There are some nice points described in the design of the measurement area - especially the use of the PGA113 when it comes to calibration and programmable gain and also the use of Schottky diodes to protect the A/D-inputs of the PIC-processor (if you are going to use a PIC-processor this is a really important step as over/under-driving the A/D-inputs outside of the tolerances will wreak havoc on the PIC-processor and A/D-inputs and Vref-generator adding an offset to all measurements, just ask Microchip about this!).
The PGA113 requires interfacing to a microprocessor to work, but the simpler PGA103 doesn't but then you won't have the calibration part, just the programmable gain via some binary input pins - a nice ic anyway.
The eTracer describes the use of the AD8479
http://www.bartola.co.uk/valves/2013...tracer-part-3/ which is another nice component to use.
These are SMD-components but placed on adapter boards they are easily exchanged if they release their magic smoke for some reason.