Well, AME includes a preset specifically for YouTube, though I've seen reports of it not working very well or giving less-than-stellar results.
I've developed several encoding algorithms for H.264 that seem to work very well for YouTube video. I've attached screenshots of the one for my SD footage and the one for my HD footage (note the very different finished file sizes). They both give very good results, and the HD version is true 720p HD. I've also got a couple of mid-range encoding algorithms, and if you'd like to see them I'll post them as well. Obviously you may need to adjust your frame size to match your timeline, or you can just use what I've got here and have bars on the top/bottom or sides. (FWIW, the HD version is a direct copy from what Vimeo recommends for their Plus users to use for HD uploads). For both of these, set your multiplexing to .mp4 and "Standard" or "iPod." Audio is 32 bit, 48kHz, 128kbps, AAC, though you could adjust that however you wish. Here's an example of the output of the HD version. Shot with a JVC GY-HM700u at 1920x1080 30p mixed with a small AVCHD camcorder at 1920x1080 60i.
I've developed several encoding algorithms for H.264
Those are actually just a collection of settings. The algorithms Premiere Pro uses for H.264 encoding are provided by MainConcept, and to the best of my knowledge are not accessible by the user for modification.
Thanks for the correction on nomenclature, Jim...