What to wear under my graduation gown?

If the blue dress isn't too short, too low cut or loaded with sequins, I'd wear that one. Blue looks good on everyone and you'll look fabulous in photos of the graduation.

Otherwise, wear the pink dress but add a skinny silver belt or add a satin ribbon sash belt to it to make it a bit fancier but not too much. Congratulations on your granduation!! : }

Look good. Then you'll feel good. Then you'll also look good in any photos that get taken of you.

It often feels like too much hassle to make an effort before an event. But then, when you're actually at the event you often wish you had made the effort. So I say wear the good blue dress.

I believe you should wear something comfortable, but still semi- fancy. I'm probably not your most reliable answer.