Les Arcs and La Plagne were both built from nothing in the 1960s and 70s, on high pastures above the Isère valley, to stop the valley's young people from leaving. Les Arcs came from the guide Robert Blanc and the developer Roger Godino, with the designer Charlotte Perriand on the architecture team, and opened Arc 1600 at Christmas 1968. La Plagne opened in December 1961 with two drag lifts and four runs, and ended up with eleven villages. In December 2003 a double-deck cable car, the Vanoise Express, joined the two areas across the Ponturin valley, and Paradiski was born: 425 km of pistes by the operators' count.
The two sides are different places on one pass. Les Arcs is the architecture side: car-free villages stacked up a slope facing Mont Blanc, a pedestrian village (Arc 1950) built in 2003 to look like a traditional one, and a 3,226 m summit above a 2,000 m drop. La Plagne is the geography side: a big, sunny plateau of blue runs, a glacier you can still ski, a rooftop at 3,080 m and the only Olympic bobsleigh track in France that tourists can ride. Five days is the right length because the cross-over takes planning: two days on each side, one lighter day, and the transfers between them are slower than the map suggests.
The plan assumes you sleep in Arc 1800 and ski Monday to Friday. Arc 1800 is the lift hub of Les Arcs and the nearest base to the Vanoise Express on skis, and the funicular from Bourg-Saint-Maurice brings you up from the station. Day 1 is Arc 1600 and Arc 1800 (easy blues, right for beginners), day 2 the Aiguille Rouge and Arc 1950 (the day for strong skiers), day 3 the Vanoise Express and La Plagne's glacier side (reds and blues), day 4 off skis in the valley, and day 5 La Plagne Centre, Aime 2000 and the bobsleigh track, planned as a one-way trip because the Express is a long way from the track. A Monday start (Monday 11 January 2027 works) avoids the Saturday changeover rush and the French school weeks; the first days of 2027 are still Serbian school break, so expect other families from home. For the country around it, see France. If you want a different area for a day, the neighboring guides are Val d'Isère and Tignes and Les 3 Vallées.