At Travelodge Pioneer Villa, Halsey, OR, some local guys whom I recently got acquainted with and who always show up in the early morning and sit at the regulars' table in the restaurant gave me this nice advice for a day trip. Go to "Crater Lake" if you wanna have a wonderful view of Oregon's beautiful landscape.
OK, I did it. With my rented Chevrolet Cruze, I took I-5 South from Halsey and left the Interstate at Eugene Jct 188 on OR-58 West. En route and after some 58 miles, you pass Oakridge but have already entered Willamette National Forest for quite a while. You can visit Crescent Lake after some 58 miles southeastbound. At couple of view points, you are able to see the Diamond Peak (8'744 ft = 2'667m). You need additional 27 miles for getting on US-97 South. From there, you get to Jct OR-138 West after 27 miles where you turn to "Crater Lake" - Chemult is almost in the middle.
At Chemult you should stop at the Ranger Station / Visitors Center (us-ranger-station) to have a nice chat with the friendly ladies there and get the extensive information, maps and travel advice you may need.
After passing Beaver Marsh (nothing special to see there), you are almost at this respective Jct to "Crater Lake National Park" within Umpqua National Forest.
Well, it will take you a while (30 miles) to get there but then you will get the most awesome view you haven't probably encountered in your life-time.
Btw, the northern entrance to "Crater Lake" is closed in winter. I was told that there is even a lot of snow in June. Yes, indeed, you still see the remains of hardened ice-snow slowly melting away.
Be prepared to chilly temperatures there - and put on your sun-glasses or other eye-protection due to the strong winds coming from the crater, blowing sand in your eyes.
You get the wow-effect for sure.
Please, make this neat "Crater Lake National Park" experience. If you have enough time visit Diamond Lake as well.
The park entrance fee is 10 dollars per passenger vehicle plus 5 dollars per passenger, valid for one week.
Enjoy the day - I did, for sure.
For your trip back you should take OR-138 West via Diamond Lake till Roseburg Jct 124 I-5 North for getting back to Halsey.
Well, my navigation system guided me back the same way I came, and I haven't visited Diamond Lake so far.