Implementing an offline guitar monophonic pitch detector
Each of the "standard methods" you listed has a failure mode (or modes) and an estimation error (which may vary with the guitar and the note). Characterize the failure modes or each method, and evaluate the estimation errors of the more successful methods, then match them to your samples, and perhaps pick the least bad (or other suitable statistical fit.)

With "the guitar in particular", one thing to watch for is that some notes on some guitars can produce a slightly (but measurably) inharmonic overtone series.  If so, the waveform will never be perfectly periodic.  This can cause successive periods of the fundamental mode waveform to never exactly match (which can throw off both autocorrelation and AMDF lag estimation methods, etc.).  Thus, one may need a psychoacoustic model to determine what might likely be the perceived pitch to a human (assuming that's what you care about).  Also, the ratios between overtone magnitudes will usually change (evolve) over time, not just decay linearly as per an ADSR envelope model, which might also affect periodicity and your choice of method.