I’d recommend you stick to the south and central coast, then, if you only have two or three days. I’d think you could enjoy the scenic Highway 42, from Ashland west to Bandon, then north on Highway, 101. If I had three days, two nights, I would probably spend the first night in Florence, see the Oregon Dunes National Recreation Area, have lunch in Yachats, then the second night in Newport, and spend the morning there (the Oregon Coast Aquarium, beautiful bridge, lovely bayfront) before heading west on Highway 20 to Interstate 5.
The town of Florence is known as the state’s center for rhododendrons. The annual rhododendron festival is May 18 – 20, 2012 this year. But the corridor of Highway 101 between Reedsport and Florence usually is awash in the flowers between May and June.