I have to laugh - I too got stuck at 29 and kept it for a few years. I also had a good excuse - I was flying to Australia to see family and the best airfare deal happened to be one where I would lose my 30th birthday in the date line as I went. So as I saw it - I did not have a 30th birthday (or cake - it really does not count without cake!!). So I stayed 29 a few more years - until it started sounding creepy.

My problem with turning 40 is that I remember both my parents 40th birthdays well (I was 17 or so at the time) where my son will have just turned 1 before my birthday. Guess thats what happens when you start so late.
I am just not in the mood for a big surprise party - be better to save it and see if I reach 50.

At least I get the bonus of fireworks and a party where ever I happen to be on my birthday - each and every year!! (One advantage of being born the night that everyone stays up late drinking and partying!!)