It's surprising that Google Now wouldn't be capable of figuring out that you're a city-dweller who takes public transit, considering that a majority of Google employees live in either the San Francisco Bay Area or greater New York City. I would think that if you requested public-transit directions to the location in question (e.g. in the Maps app), Now would figure out that you were likely to be taking public transit. (That's just a guess -- I work for Google Maps, but I don't know how much information Now gets from it.)

Google Maps, when you ask it for directions (by whatever modality), will certainly take current traffic conditions into consideration in recommending one route over another. And it'll take historical traffic conditions into consideration in predicting how long it would take you if you left an hour ago, an hour in the future, two hours in the future, etc. But it doesn't do the proactive "time to leave for your 10:00 appointment" thing, which Google Now does.