Senior Adventure

This island near Athens abounds in trails.

One can also hike the Ring of Kerry in Ireland.

Dachstein Rundwanderweg - An eight day loop in the Austrian Alps, although segments can be tailored for the time you have.

Austrian Alp Huts - 

The Grand Sentier de la Côte Bleue connects Marseille to Martigues over 68 km of trails. Trailheads are accessible from local train lines.