Especially with a small child, my views on Crater Lake become even stronger. In my view the big issue is time. If you plan to get from Crater Lake out to US 101 in time to see anything of the southern Oregon coast (the best part IMO) the drive is very long, generally considerably longer than the mapping services (Google, Bing et al) show. It can make for a very long day, and, honestly - just my view - Crater Lake can be a "two hour" national park for many people. Your call, of course.
For a compromise, let me just offer a compromise that will give you some terrific "old west" scenery but which will reduce drive times a little. Here's the revised map -
https://goo.gl/maps/CS3gpu8adE3NWpbLA
What this does is include Smith Rock State Park, near Bend. Smith Rock is a stunning - and quite convenient - area of dramatic rock scenery. Here's a picture (not mine) of what it looks like.
This would let you use the McKenzie Highway (SR 126) to cross the mountains to Eugene, then south on I-5 to OR 38 thence out to the coast. I'd give this route a very high rating, compared to many hours more in the car in order to get just a short time at Crater Lake.
As for my choices of waypoints on the map, mainly they're just to show the driving route. The revised map shows Bandon, in my view (and that of many others) the most attractive town on the southern Oregon coast. The use of Oregon Hwy 38 is because it's the fastest and most scenic route between I-5 and the coast. One particularly interesting thing is that you'll pass a wildlife refuge just as you're approaching Reedsport, where (particularly at this time of year) you're likely to see some Roosevelt elk grazing on the flats. There's a well marked pullout and viewing platform there.
Once you're in the redwoods, I'd probably suggest looking at the Eureka area - Trinidad, Eureka itself, or picturesque Ferndale, a little south of Eureka, as overnight locations. With a small child, I'd probably suggest Eureka, especially that would let you visit the
Samoa Cookhouse in Samoa, across the bay from downtown Eureka. This is a fun restaurant in the mess hall of an old lumber mill, with hearty food served family-style by grannies with attitude. Fun place for all, especially kids.
The Avenue of the Giants is a must-see "detour" that parallels US 101 for quite some distance. It will knock your socks off.