No trip to Canberra would be complete without a trip up the Telstra Tower! Unfortunately, they charge to get in and have the windows frosted so you can't get a free peek at the view. But if you eat at the restaurant, you can see the view from the revolving restaurant and also go outside on the viewing deck, and the food is pretty good.
Biking around the lake takes about two hours and is an extremely pleasant way to spend an afternoon in Canberra. In fact, if you enjoy biking, this is the city for you. The lake loop is only one of many linked bike lanes that take you through gently rolling parks. The sunshine and somnolent atmosphere will ease away the tension of whatever happening place you come from.