I think the Katy is an option, and there is a 40+ mile trail (paved) east of Missoula that is not a rail trail but is very nice since it keeps you off U.S. 93.

One thing I have noticed over the years is that, at least on the Atlantic Coast route, is that it has included trail miles for the sake of trail miles. For example, south of New Paltz, NY, the route now uses the Wallkill Trail. Boring and not the best surface. The worst part is that it end in the middle of nowhere, and you have to loop around and then take some not so nice roads to join up with the old route. I made the mistake of following the new route in 2018. Not fun. In 2021, I followed the old route, like I had way back in 1999, and it was far, far better.

Another example is also in NY. The routing now uses the southern end of the Harlem Valley Trail. Fine. It keeps you off a shoulderless highway for a little while, but then it puts you on busy roads with truck traffic to get you back to the original route. I plotted a benign dirt alternative from the end of the trail that is really nice and much shorter. It should at least be shown as an option for people with bikes that can handle unpaved roads.