I was going to argue with the first sentence above until I saw that you included what you have been saving as an "expense", which it really is not -- what you save is the excess of what you earn minus what your actual expenses are (other than spend or save, what else could you be doing with it? ).

From the standpoint of actual expenses, I expect mine to go up in retirement, mainly due to travel and hobbies. For ten years now, I have lived about 4 miles from work, so have almost no commuting expenses, and we spend very little on vacations and entertainment. The house is paid off, kid out of college in a few months, so our expenses have been pretty stable for a while.

Most of our activities are also pretty cheap, involving walking, running, biking, and so on. We are not cruise, beach, golf, or resort people, so won't be spending money on big vacations. The most likely scenario will be travelling to other places to ride or hike for a few days at a time. So I expect to spend more on travel, but not extravagantly more.

Of course, since almost all my income will come from our investments as opposed to a defined-benefit pension, the thing that makes me most nervous is the possibility of those investments going down too much in a recession or worse. No matter how much you save and plan, there's always something to keep you awake if you think about it too much.