I can offer some help near Klamath Falls.
If you come up 97 its okay and you CAN take it all the way to the Crater Lake Junction about 24 miles north of Klamath Falls. I guess if you have never been along it before, the stretch north of Mount Shasta is nice, and north of Klamath Falls you travel along Klamath Lake and there are great views.
If you want something a little less "highway" you might want to head west out of Klamath and take Highway 140 to Westside Road. This runs up the west side of Klamath Lake through some lovely forest and is just a nicer ride IMO. Beyond the N. end of Agency Lake you take a jog east to near Fort Klamath and are then on highway 62 which takes you right up to the S. entrance of Crater Lake NP.
39 N. out of Canby is pretty straight, I find it rather 'meh', but it takes you right near Lava Beds NP. the roads in the park are very nice, but the speed limits are quite low. Again, if you have never been there, definitely worth checking out, and if you need a place to camp, its nice. Also, you pay to enter the Lava Beds, the receipt gets you into Crater Lake free (and visa versa) for seven days.
I'd say all the roads west of Crater Lake are pretty fun save for a long straight stretch of 62 west of the S. Park entrance.
BTW, the S. entrance is plowed and kept cleared all year around. The Rim Drive usually opens mid-July, but we've had record breaking LACK of snow this year, and record breaking high springtime temperatures, so you may be able to ride the entire park. They plow the west side of the rim drive to the N. Entrance junction, then work towards the N. entrance and clearing the E. side of the Rim Drive.