Laax is about two hours from Zurich by public transport. Take the train to Chur (about 80 minutes from Zurich), then a PostBus to Laax Murschetg (around 40 minutes). In winter, direct ski buses run from Zurich on winter weekends. By car from Zurich, follow the A3 then A13 to Chur, then west on the Flimserstrasse — about 90 minutes in light traffic, longer on winter Friday evenings when the road through the gorge gets congested.
The nearest airport is Zurich (ZRH). Geneva is possible but significantly further. Car hire from Zurich or Chur is the most flexible option for families with ski equipment.