As someone who travels a lot, I like your top three things, especially the first. Though taken alone that starts looking a lot like a directory of directories. One problem, as you say, is that there's a lot of information out there but it's uncurated and often based on specific commercial interests.

I just discovered Rome2Rio on this thread and it seems useful for things like whether I can take a train from A to B or whether flying makes more sense.

I use Tripit for much of my organization but it obviously only captures some things and it's format for displaying a whole trip is moderately awful.