I don't have a place that I would necessarily keep it but I have a list of characteristics that I think would make a good place as well as a number of places that I would try to avoid. You can find all of those in this article I wrote about it. https://www.whatisbitcoin.com/security/store-your-seed-phrase

Also, I think there are a lot of good ideas in the geocaching community that are next to impossible to find unless you know that something is in a specific location and you know what to keep an eye out for.

There are also a lot of hidden in plain sight sort of products that you can buy that look like a soda can or a head of lettuce but those are probably best suited for people who live alone.