I'd agree with running YPAO, and then reviewing what it says and possibly doing some manual tweaking.
As others have said, the sub-woofer settings from YPAO may well seem odd, especially the distance setting. But, this may still actually be a good setting, based on room issues, reflections, sub-woofer location, etc. trying multiple YPAO "runs" with the subwoofer in various locations may be helpful. But, playing with the subwoofer settings manually is probably worthwhile.
The YPAO for the RX-V750 is "partial YPAO", without parametric equalization. Unlike the higher-end models, you are not getting any frequency shaping - just speaker "size", level, distance/delay. On the one hand you are missing out on the chance for YPAO to clean up some glaring room-response problems. But, some purist-types might argue that the less signal processing, the better!
Your receiver DOES include a graphic equalizer function for just the center channel, which in principle could be used to achieve better timbre match between your center channel and the fronts. But, YPAO makes no attempt to do this, and leaves the center channel Graphic Equalizer "flat". Further, there are no separate built-in test tones for each band of the graphic equalizer, so it's never been clear to me what the best method would be to try and manually optimize things. If you have a CD or DVD with audio test tones at different frequencies, that would help in manuall setting the center channel GE.
