Want to have a proper celebration for my DD2 and DS3 13th birthday (birthdays!) and I'm suddenly at a loss as to what to do for it. I don't think they're especially bothered but they're my youngest and I feel like this is the last birthday they'll tolerate spending time with us primarily so maybe I'm getting all misty in wanting to do something special. As a twin, I know the difficult balance between celebrating them together but also as separate people. Always used to do outdoorsy gender-neutral things when they were younger (they are a boy and a girl) and I can't really remember what I did for my other DC's 13ths! 
Any advice would be appreciated!