Prior to hearing what GRRM based off of. I guess here is how I sorta saw everything.
Rivermen - I have always liked these guys and always feel like they are seen as worse than they are. -That being said I kinda always pictured them in a Welsh/Briton manner, more Celtic in their clothing design, etc. or so I’ve seen them in my head ( if that makes sense)
Stormlanders - I’ve seen them as inherently Scottish. Can’t explain why, but that’s how I assigned them and did Bobby B’s voice in my head
The North - Northern England/Norse
Westerlands - English
Iron Islands - Irish
The Reach & Targaryens - French.
I could go on and on, but I want to open the floor up to everyone and see what y’al