From a technical standpoint, to get the leather black the tanner must add pigments to the leather, the more pigments added to the leather the less it will breath. Making the leather less comfortable and also doesnt age nearly as well as aniline or vegetable tanned hides.

We have a black leather couch in our LR (which opens to our kitchen), black counter stools (w/chrome legs) in the kitchen itself, and black and chrome chairs in our DR--works for us! Seriously, they all look great in our space, and we couldn't imagine anything else working as well with our color-scheme, or decor.

Black leather is very classic and works with many design styles. If that's what you like, go for it. However, the kitchen having a lot of black would make me want to add more color as not to have an overall feeling of everything being dark. So many colors work with black, from sage green to burgundy, yellow or cream, and all look good paired with black accents. If you feel you need black in the living room to tie it together, you can always do it with accents.

Our previous home had a family room done with black, white, red and green with touches of yellow. The fabrics were all from Waverly. The main one was Garden Images in black, and the Ballroom plaid with the same colors, along with textured solids. It worked really well. Keep an open mind but remember the only one that really has to be happy with the space is you.