I'd argue that if you go with Fallout (which I'm all for) then you'll want to put a lot of points into Charisma to get the ideal number of choices. Higher charisma means better NPC interaction. Better NPC reaction means more choices.
Same with intellect actually--you'd end up with more dialogue choices from that as well.
So, my vote is if you want a Fallout experience that is best designed to create options you'd have to jack up Perception, Intellect and Charisma.
Then again, it's been a long time since I finished a playthrough, so I may be remembering this wrong.
On a totally different note, my favorite RPG ever is Planescape--but that seems more suited for a different kind of essay, so I'm not sure I can really vote that way. I'll save my vote so that I don't waste it on a third party when the voting gets tight.

You would make a great undead minion

I love you too, lich.

B-b-b-bump

I would throw a fireball in your face right now .If i was not busying dealing with a group of paladins.
paladins there like bugs kill one and then you get a army of them on your door step.

KoDP LPs are sick, I vote for that. Especially if you can weave it into a bit of a narrative.

Fallout 2.

Votes updated!

Fallout 2 is the one I'd be most interested in, though that's mostly because I can't be bothered with the damned temple.

I'll probably do one eventually anyway, when I have the time. Of course right now I'm more interested in getting an essay written hah.

I would recommend deux ex also as it's near the end of the term and fallout 1 and 2 would take maybe 2 months. It would also allow some interesting philosophical discussion about the community and their reasons.
You could record and stream it live using a streaming site like ustream or JustinTV. JTV has email alerts of your shows and it has a bigger screen that people can watch.

I'd enjoy watching you LP Fallout 2.

It is a hard decision for me, and it depends a lot on which direction you would want to go with the LP. I'll give a few choices, then give my definitive vote (to make tallying the vote possible).
Knights of the Old Republic is a safe choice if you aren't certain what your professor likes. Everyone has heard of Star Wars, so it makes explaining plot points much easier. You will spend less time explaining what is going on, and more time actually describing your playing, which is possibly a very good thing. It is always easier to write an LP about a subject people are more familiar with.
Baldur's Gate would be really interesting if you are planning to compare and contrast gameplay in that classic RPG with newer titles. Some of the dialogue choices would be fun to write up as well. No matter which way you go though, BG has a solid story, so it is hard to go wrong with it.
Vampire Bloodlines is really cool because it really is a dark game, with many options available to really mess with people. It really isn't "Should I be good or evil", but "How evil should I be THIS time". Also, vampires are totally in right now! :P
But, I would probably pick Master of Orion 2 as my first choice, all else equal. MOO2 would be really interesting, since there are far fewer LPs for strategy games (at least I haven't seen many, none if you don't count Dwarf Fortress). It would really allow for a lot of freedom in the narrative, if that is where you want to go with it. It would be fun to describe AI actions and give them some made up motivations. But, of course, it is only good, in my opinion, if you are playing a story based LP, rather than just listing your moves and the consequences. I would love to read an LP about MOO2, just to see how a person designs their ships and builds their colonies.
Note:
I just noticed my runners up are all pretty much by the same group of people (Bioware/Black Isle/Troika), but my winner is completely out there. Not really of any consequence, but it is rather amusing to me, at least.

Votes updated! I'll be closing the votes soon.