The Greyhound buses travel between Squamish's not-very-conveniently-located Garibaldi bus depot (Google maps), Whistler Creekside, and Whistler Village.
Departure times from Squamish are daily at 8:50am, 11:50am, 3:50pm, and 9:20pm. Departures from Whistler are at 10:00am, 1:00pm, 4:30pm, and 7:45pm. Travel time is 55-70 min.
Book online, for much cheaper rates, starting as low as $6 each way but typically closer to $8.50.
This round-trip-only bus departs at 7:00am from Pemberton Ave. between 2nd and 3rd, does a pickup at the Executive Suites Hotel, and drops riders off at Whistler Creekside and Village at around 7:50. The return trip leaves the Village at 5:30pm.
The return trip cost is $25 if paid in cash or $20 if booked online (choose "Squamish Commuter to Whistler Creek and Village to Whistler Creek" as the origin).
Pop Rideshare (previously named HitchPlanet) is a Vancouver-based Uber-like service that connects you with people who are making the drive and have an extra seat. It is an excellent, inexpensive, fast, and convenient option to get from Squamish to Whistler and back.
The only question is whether you'll be lucky enough to find a driver who's got a seat available for the time your looking for. Typically you'll find a few rides available every day, and the number is increasings as Pop Rideshare continues to grow in popularity.
Rides typically cost $7 dollars each way and the drivers are often flexible on pickup and drop-off locations.
Hitchhiking from Squamish to Whistler and back is common and in both cities there are traffic lights along the highway which slow down traffic and increase your odds of hitching a ride.
Unless there is a sign posted indicating otherwise, as long as there is a wide shoulder on the highway, hitchhiking is legal in BC.
Starting this 2016/17 ski season, the Squamish Adventure Inn will be offering rides between Squamish and Whistler, departing Squamish in the morning and returning from Whistler in the afternoon (check here for up-to-date schedules).
The cost is as low as $8 return (i.e. there AND back) if you book your seat at the same time as you reserve a room. Otherwise it is $10.
Did we miss anything?
Let us know in the comments if you have any questions or think we missed something.