The nicest way from Yaletown to False Creek is the Aquabus, which has a dock right at Yaletown. The creek is also only a short stretch away on foot, so many people simply walk down to the water and follow the seawall.
Aquabus from the Yaletown dock
Aquabus is a small ferry service that runs on False Creek and stops at eight docks: Hornby Street, Granville Island, David Lam Park, Stamps Landing, Spyglass Place, Yaletown, Plaza of Nations and The Village. Yaletown is dock 6. From there you can cross to Granville Island, or head the other way toward Plaza of Nations and The Village near Science World and Olympic Village.
Boats run roughly every 5 to 15 minutes depending on the dock. You can pay on board with cash, debit or credit card, and mobile passes are sold through Token Transit. Operating hours and any seasonal changes are posted on the Aquabus website, so look there before you plan around a late sailing. A competing operator, False Creek Ferries, also runs on the creek.
Walking or cycling the seawall
Yaletown sits on the north shore of False Creek, and the Vancouver seawall runs along it. The same path continues past Olympic Village toward Kitsilano and Granville Island, so you can walk as far as you like and stop wherever the water looks best. A map app will give you a distance and time for the exact stretch you want, and that is better than a rough guess because False Creek is long.
Mobi, the city bike share, has stations around downtown. Check the Mobi map for the nearest docks to where you start and where you finish.
Canada Line from Yaletown-Roundhouse
The Canada Line is part of the SkyTrain network, and Yaletown-Roundhouse is one of its downtown stations. Going south, the next stop is Olympic Village, which sits on the south shore of False Creek, and after that comes Broadway-City Hall. Going north, you pass Vancouver City Centre before reaching Waterfront. This is the quickest option when the weather is poor or you are in a hurry.
Fare information and live departures are on the TransLink website and app. Their trip planner will also tell you whether a bus, such as a route running along Davie Street or Pacific Boulevard, makes more sense for your start point.
When a car makes sense
If you are carrying luggage or heading to an event with a crowd, the Vancouver taxi page lists cab options, and the Uber estimate calculator gives a rough figure for the short hop.