Some options include:
Hiking
Tamanawas Falls
Lookout Mountain
Cloud Cap Trailhead
Rowena Crest
Biking
Mosier Twin Tunnels
Historic Sites
Timberline Lodge
Shopping, Exploring
Hood River (shops, galleries, food, kite boarding!)
Orchards & Wineries
Fruit Loop
Or ... do it all (like this New York Times writer -- travel to wineries by bike!)