Geneva airport is the closest. If you are driving, it is just over 1.5 hours. Follow the signs to Lausanne, then Vevey, Montreux and Villeneuve. The next exit is Aigle. The mountain road to Leysin is well signed.
Swiss trains are great. Fast, and for real comfort take first class, which is not very expensive. Alight at Aigle, and take the mountain train to Leysin. Now that is fun.
Mayen Tours and Endless Ride. LatLong: 46.3459984, 7.0142555