We drove the Mt Hood Scenic Loop today and it is well worth doing if you are in Portland. The roads are excellent and the entire trip is picturesque. Make sure you take the spur to Timberline Lodge; the views of Mt Hood from the lodge are the best you will get. The road is good, but a bit challenging; it rises 2,700 feet over 6 miles!
Coming back to Portland you can stop near Bridge of the Gods to buy fish that was caught that morning. If you haven't already seen the waterfalls along the gorge you can finish your tour with those.