I use a 13" MBP with no UI magnification, but most web pages scaled to around 200%. That keeps the UI nice and compact and leaves a lot of screen space for actual content (about 2170x1523 with my current browser layout). I do occasionally set it to a scaled resolution when someone else has to watch/use the machine as well.
I couldn't agree more, I was given 16:10 monitors for my current job and I'm not sure if I'll ever go back to 16:9 if I can avoid it. Next laptop is a 13" MBP for sure too.