Practical
Traffic math and a separate lake
Write 'about an hour in fair traffic' on the plan, then add a second number for the hour you are actually travelling. Late afternoon toward Vancouver, and Friday toward the valley, both punish optimism. If you must make a flight at YVR, leave as if the highway owes you nothing. A Sardis room does not move the airport closer. It moves you onto the highway in the right direction.
Cultus Lake Road is the local summer bottleneck. The park and the shore have limited patience for people who arrive at noon on a hot Saturday expecting solitude. Go early, or go on a weekday, and keep the hotel booking in Chilliwack if that is where you are sleeping. Downtown and Sardis both have food. The lake has a beach. They are a set, not a single address.