Tokyo: Good option, though the problem can be that Tokyo is too big even without tourists watching Olympics.
Madrid: Good option, not too big city, not too small.
Prague: I'm not sure, maybe a good option. Is there a big enough venue for Olympics?
Chicago: Interesting option, maybe better than the biggest US cities because it's not too big.
Rio de Janeiro: Too bad gang wars in the slum areas IMO.
Nairobi: If logistics work and there is a big enough arena, why not?
Cape Town: What about the winter that is during Olympics in South Africa? Could cause problems.
Baku:

Doha: At least there would be hotels that the sportsmen could use. Money wouldn't be a problem.
Bangkok: Interesting option, though Thailand isn't among the biggest sports nations.
Dubai: Same as Doha.
Rome: I don't see any bad things in this, though Italy just had winter Olympics in Torino.
Hamburg: Why not?
Leipzig: IMO not as good option as Hamburg.
Lisbon: This is a good option too.
Istanbul: Not bad at all, safety may be the only issue.
Montreal: Great option IMO. Though Canada could fit better to winter Olympics.
Toronto: Same as above.
Monterrey: Why not, though I don't think it will qualify to final election.
Buenos Aires: This is a good option too.
Santiago: As is this.
One of the Australia Cities: Sydney just had them at 2000.
Korea/Japan: South Korea just got winter Olympics. Edit: Sochi got them... So now, why not?
I voted for Nairobi, could do good things to Africa if Olympics were held there.