Having turned 50 myself, I say the most important thing about this outfit is that YOU feel great in it. The special nature of the event calls for something memorable that maybe you've never tried before. But ONLY if you feel a little tingle of excitement when you put it on and look at yourself in the mirror.
I know those sound like intangible values, but I think you'll know it when you see it. Might be a dress,, might be a pants-jacket-tunic-top combo, might be an exciting pair of shoes with a more subdued garment...not knowing your taste, your community, or your body shape, it's hard to be totally specific. Most of all -- have FUN! That is Angie's mantra and the guiding principle of YLF.