I'm working with a client to finalize the plans on her new house and she doesn't have a formal dining room. In fact, she's the third client this year to build a house without a dining room. I'm not sure I'm ready to see the total loss of dining rooms, but I would love to see their purpose change. To give a family more than one reason to use them, not just for Thanksgiving and Christmas. A trend I'm seeing is having a dining room that also serves as your home's library. I love the look of this, but who really has such a collection of books they need a library? Maybe incorporating storage for china, along with books makes the best sense.
I like the idea of using a dining room as an office. Now, this only works if you can keep your desk (aka dining room table) neat or you have doors you can close. This looks like a great place for homework as well, especially if you have more than one child trying to do homework at the same time.
To me though, the best way to to easily use your dining room is to keep it comfortable. That means, stay away from the set of eight matching wood chairs. Bring in upholstered chairs and maybe less of them. Ballard Design sells a great folding chair you can bring out for additional seating when needed. Select a wood finish that is distressed so you don't need place mats. Instead of a traditional chandelier, hang a lantern or a group of small lights over the table. Here are some "non-traditional" dining rooms that I love.