Well, thinking ahead and planning these things also helps save money in the future. My wife and I knowing we might have children already bought a house with extra bedrooms so that we could have children here. We also made sure to buy in a great school district (so we won't need to pay for private school if we don't want to). On a side bonus, it also made our house extremely easy to sell, since people are lined up to move into the neighborhood. And as a double bonus, since it was our first house, it's the cheapest on the block, making it even more likely to keep it's value.

Utilities are a good point, I like to keep the AC and heat low since I just hate to think of the money being wasted, but I wouldn't want to freeze/melt the kids :)

As for cars, we'll probably need to upgrade one at some point in time. We have a 4 seater car, but it doesn't have much extra space, so vacations would be difficult. I'm thinking I could trade in the 3 seater pickup for a more expensive 4 seater for any larger trips that are needed. That's a good point as to a cost I'll need to think about.

I've saved all my books since I was a baby (well, I admit my parents saved the books from when I was younger), so I have a large enough library now to keep a kid busy for years. I'll just keep praying that my kid will like to read half as much as I always have.

Our medical plan will require some changing, but since my wife and my companies both offer health care, I think we can switch things around and not cost ourselves too much money.

Someone mentioned that they don't spend much on items, but more often on learning and experiences. I like that approach. I have spent quite a lot of money on classes on myself and have never regretted it, so I'll be happy to send my kids to music lessons, scuba lessons, karate, dancing, etc. The main purchases I've regretted were all objects that I thought I would like and never really got my money's worth out of them. I'm hoping they'll end up with some of the values I've picked up along the way.. we'll see :)

An interesting side note: I spent over 12k last year in Scuba diving expenses (went from never dove to an instructor in about a year.. very intense, lots of diving). I love the idea that I learned so much that year, and even if I don't dive for the next 20 years I'll be glad that I went through the experience. However the few thousand dollars of gear that I haven't used in a couple months is really bothering me. Just interesting how objects don't maintain their value nearly as much as experiences do.