Man thats a hard one. I would love lessons from Jimi,Stevie,Billy Gibbons, Dimebag but at the moment for the style of music I am into curently would be Guthrie or John 5. Both those guys are freaking amazing and versitile and understand the fretboard like I would like to one day.
Like many others Paul Gilbert...not because he is amazing, he is, but because he is also an amazing teacher (watch anyone of his videos). Teaching is a lot harder than it looks and I have a feeling that a lot of my personal favorites (Yngwie/Schenker), don't really know what they're doing, as they've never taught, so the lessons would go: "I guess I do this, well, maybe this, hmm, let me see".
Great choices, some expected, some practical and wise.
I'd say Greg Howe, though I'd ask him to keep the focus on his meldoy approach, etc, not so much his rediculous technique stuff, lol. He's just so different harmonically to me than many others I also love, think there'd be some great inspiration/learning to be had.
Yngwie would be, well, entertaining/fun!
Tony MacAlpine (one of the best melodic phrasers) would probably be way beneficial as well.
+ 1 - I think he has a good combo of musical knowledge/theory (which I could use) and creative insight and a teaching style that I think would be grasp-able.