Resistor switching methods
More cost efficiency (this feels like code golf):

only 1 control line
only 1 transistor (N JFET or P MOSFET), 1 R and 1 C
infinite number of possible measurement ranges
can get rid of the ADC, if it isn't needed otherwise (see below)
needs calibration and could be temperature dependent, but the same goes for the switched R method at a lesser extent (so it depends on your desired level of accuracy)
1kS/s is ambituous with an MCU (needs fast control clock)


How does it work:
By controlling the duty cycle of control, you vary the DC gate voltage and therefore tune the resistance of the FET in a continuous fashion. You can also use feedback to bring AtoD to some defined voltage (e.g. VCC/2) and then your Duty cycle gives you the value of R1 (via a conversion which you have to establish once).
Down the road, you could even scrub the ADC (save costs) and realize the feedback with a comparator, so your MCU can read the duty cycle directly.