I'm an adult and a birthday is just a birthday. My parents never celebrated by my birthday as a child - although my siblings had their birthdays celebrated - so any celebrations I've had in my adult years have been very low key, which is fine by me. Most years, I don't do anything to mark the day. It's just another day.
However, having had a really tough few years, this year I'd like to do something for ME. So I've decided to booking us a nice holiday and go above the usual budget for the occasion. I'll be going with DP and two young DC. If we fly the day before my birthday, the only flight time gets us there in the evening so we wouldn't reach the hotel until 9/10pm, with two tired kids in tow, and we'd lose the first day but still have to pay for the hotel which is pretty expensive. Does mean I can wake up on my birthday hopefully somewhere nice and have a relaxing day. If we fly the next day, on my 40th, the flight time is much better and we'd land after lunch and make the most of the rest of the day.
I am an adult and I know it's just a birthday and not a big deal. Head tells me to book the more reasonable flight to arrive after lunch. Downside is obviously I won't be relaxing as I'll be getting up early to get kids ready, travel to airport, keep kids entertained on a 4hour+ flight (DP is rubbish at this), sort out car hire on the other end, get to the hotel etc.
Tell me IABU to even consider that my 40th is relevant when choosing the most sensible day to fly on! Please be gentle :)