The latter example is certainly going way out of the way...if it had occurred a few years earlier, there would have been a lot more more direct options. Nowadays, there are less and less.I think I have a couple to add for the California Zephyr.
Denver to Omaha on the Union Pacific. I believe I've seen that that's been used a few times.
The other one I have I've only heard of once: Ottumwa to Galesburg via what now the Canadian Pacific to Kansas City and then the regular Southwest Chief route to Galesburg. I thought I had seen a photograph of this occurring, but searching only found a mention about halfway down this page.
Another 'short' detour the CZ has taken in western Iowa, between Council Bluffs and Malvern via the N&W (former Wabash). Another line gone.