i like leading into PFR's with anything that is a favorite over TPTK. whether its set, two pair, overs+flush draw, straight flush draw, etc.

but at the time, its never too wrong to go for a check raise sometimes.

as for the original hand, i think you played it fine up until the river. his small bet makes me think he doesnt have a higher set or a straight, so i would go allin after the $20.