library is strictly book storage, thats it, with a balcony at top.
Kitchen has some cool stuff, and the oven.
For my first house, I was doing alchemy theme, so I went with greenhouse, alchemy tower, and library. The kitchen was good, but saving that for my family home. Kinda wish I made falkreath my family home, but oh well.
The library really bumped me out.. I pretty much bought the DLC hoping to finally be able to build me huge library with all the books in the game.. just be surrounded by bookshelves... and all you get is a small alcove with a few shelves squeezed in there.. very disappointing :(
Sooo.. I think I'm just going to do like that youtube dude with the skulls.. screw furniture and just cover the entire house floors with books.
I disagree about the library sucking, there are 22 shelves, with space for 11 books on each. 242 books is quite a bit, plus there's a chest or two as well. Now, I was annoyed at not being able to have both the library and the armory, but as my current character had more books in his inventory than weapons....
It would have been nice to have an entire wing with bookshelves, but it's the best option if you want a place to display all the books you have.