Getting in that early (that's when we got in on Monday), just be aware that your room won't be ready until 3 or even 4. So you need to be prepared for that! They'll take your bags at Bell Services (even before you stop in at the front desk), but if you swim you won't have anywhere to change other than bathrooms, etc etc.
And it took about an hour from catching the bus to getting off the bus, and that included all the airport stops (they stop at each terminal).
By the way, if there's ANY way to change that flight, do it. I don't know where you're coming from, but catching our 6am flight from seatac meant getting up at 2:30 to make sure we could park the car, get the shuttle, etc etc, and it was AWFUL. Then you can't even get to the room and we were absolutely wiped out! Took us until Wednesday to really catch our breath.