Les Arcs is 150km from Geneva International Airport, about a 2 hour direct bus ride. It is 620km from Paris where a TGV train can be caught to Bourg Saint Maurice Station in under 5 hours.
On Saturdays the Eurostar from London operates into Bourg Saint Maurice Station, taking 8 hours. From Bourg Saint Maurice it is a short bus or taxi ride to Les Arcs.