If you're staying downtown, I'd recommend either taking a taxi or the bus, walking is too far.
Times depend a lot on the time of day, whether you'll find traffic.... but generally I'd estimate about 20 minutes for taxi and twice as long for bus, just since the bus also makes stops along the way. It might take less, of course... or more if it's around 8-9am and 5-7pm, when people go to work and go back home.