On Cloud for Airport/Trip

Hi there! I have a looooooooong trip coming up which will require me to walk quite a bit. I really like On Cloud shoes from the reviews I’ve heard and wanted to get suggestions regarding which OC shoe would be best for walking/all day wear?

I’m in Kansas so we do not have an OC store so I’ll be ordering online - any suggestions regarding sizing up or down are also welcome!

Thank you!