I fell in love with this area back in the late 1990s.
Ridden many routes - driven others.
First off -
Hwy 140 from Klamath Falls to Beatty is not the best choice - esp with youth.
Narrow, few shoulders, moderate+ and fast traffic, blind hills and curves.
You can take the OC&E Trail out of Klamath Falls - first 8 miles paved, then gravel.
One of the most beautiful rides in the region is along the Sprague River - from Chiloquin to Beatty.
From Klamath to Chiloquin - US 97 has shoulders but very heavy traffic - West Side Road is better.
East of Beatty, Hwy 140 has less traffic, but still pretty high speeds amd little shoulder.
Second -
Instead of Hwy 139, you can loop south from Merrill and head thru Lava Beds NM.
Since much of this loop is heavily forested, the open vistas are a treat.
Further south on Hwy 139, you can take Lookout Road to either Adin or Bieber.
Almost no traffic and you miss the Hwy 139/299 section which is a little busy at times.
Eagle Lake should have plenty of water after two wet years - great desert lake.
Third -
I love US 395 in this region - wide open and remote - like Nevada.
There's a back road east out of Susanville to Litchfield - country store.
I can't remember if the Termo Store was open when I went thru. Be good to check.
Fourth -
The east side of the Warner Range is awesome - Surprise Valley Road
No good way to get to Eagleville without dirt - so it may not be possible for y'all.
Fandango Pass Road is hardpack - big climb coming from east then great downhill to US 395.
Lakeview is a friendly town - Hunter's Hot Springs north of town has pools and camping.
Best - J