I know that others will disagree, but I have flat paint in my kitchen and have had no trouble with it. Currently my backsplash goes to my upper cabs so everything surrounding food prep is washable. However, even when I had a 4" backsplash and paint above it was easy to clean. I personally don't care for sheen on walls. If you have rooms flowing into one another, not sure that the change of sheen will look good.

linelle, I have flat paint in my kitchen and dining areas as well. I love it!! The kitchen is mostly cabinets and backsplash anyway, with very little "painted" area. I used flat paint on the ceiling, too. I didn't want the transition of going from one sheen to another, and I also think it looks better to have all one sheen when you have an open concept floorplan.

janesylvia, just use a good quality washable flat paint. I used BM Aura and it washes up great.

Flat paint is also easier for touchups.