I would just go US ANSI and use OS layouts to toggle usage of ÖÄÅ when needed. I have a 60% just like this and hitting Gui-Space on Linux and Shift-Alt on Windows every now and then to type ÖÄÅ is simple. As a plus I can get to buy regular keycap set basekits and skip the international kits.
The only problem I have with this is a that somehow when I use the Win key on Windows 7 it seems to flip my input language, need to investigate why it does that.
I'm from Finland but as a programmer US ANSI just makes more sense.
I don't know if anyone cares, but I have been using this kind of layout for my HHKB for a while now. http://www.keyboard-layout-editor.com/#/gists/5f8d010e633119104ff2f8310670cbfa
As a finn I only need special letters Ö and Ä so it frees me from using Å altogether. Currently I'm using blank keycaps, but if I wanted, I would just need 4 ISO-Nordic keycaps in addition to the normal ANSI set to make the keycaps to match (I think I could live without the custom bracket keys).
Also to ojrask: I don't know if this helps but at least for me Windows-key + Space changes the input language.
EDIT: Ofc if you are a full-time programmer it probably makes most sense to just change between OS input languages when needed.
Gampela: That looks nice! Not too many changes needed.
Overall, I'd say that I'd like to avoid switching language in the OS too much. For me, it just feels like it breaks the flow. Also, I kinda like having Swedish letters on my keyboard, but yeah, it's a hassle when it comes to keycaps. I'm also very picky about having the AltGr key.
Well, I just received a shipment of MX Lock switches and it struck me that it might be interesting to have a lock key switching between US ANSI and, in my case, Swedish ISO directly on the keyboard. In that case, there'd be no need to do so in the OS. Has anyone tried this?
As a sidenote. When GMK Nautilus dropped, I tried combining existing keyset keys for a hybrid:
https://www.massdrop.com/buy/massdrop-x-zambumon-gmk-nautilus-custom-keycap-set/talk/1744671Not too pretty perhaps, but it'd cover most symbols. An interesting experiment if nothing else.
It's really interesting to hear how and why you've used ANSI/ISO!