I play on a 30 inch screen with a native res of 2560 x 1600 but on xyson the ui is way to small to play at that res. so i play at 1920 x 1440 res, which is a windowed 4:3 aspect res.
Now, games that have scaling UI's, one is World of Warcraft, it just has a slider that increases the ui scale on a global level.
Star Wars : the old republic - has a really good totally customizable UI system, i wish more games were as good as that one, each frame can be resized individually, moved about etc.
Both these games have a free to play option (wow upto level 20) so you can check these both out and it wont cost you a penny cept your time ofc