The vast majority of my fixed expenditures are real estate taxes and insurances (over 10,000/year). Next comes utility bills and cable/cell/internet which is expensive and complicated for 2 homes. I only expect these to go higher. I have a friend who is 10 years older than I, with the same insurance, and it's $300/month more. So I don't really buy the thing about expenses decreasing with age.

Of course, if I had kids I would expect that expense to phase out... but if you take that out of the equation I'm not really sure why they assume that we'll spend less in retirement, especially if you're debt-free before retirement.

Here's a topic that's a bit touchy, but worth discussing:

How will the people around you affect your retirement funds? It could affect the location you retire to (Naples,FL vs smalltown, USA), it can affect your activities (fishing in Canada vs fishing in the creek) and affect how much you spend on food, clothes and entertainment in general.

With the right set of like-minded friends, you can spend the day bike riding and the evening playing a board game and have just as much fun as anyone else. But does that mean you have to give up your uber-wealthy friends?