I went to my senior prom. Left early cause it was rather dull, the food sucked, the music sucked (can we say 2 Britney Spears songs and an N'SYNC song too?), and it was too expensive. That was the only dance I went to throughout ALL of my school journey. And it wasn't worth it. Oh yeah, I guess this could weigh on the decision - I didn't have an official prom date for this. Went by myself. I don't know what taboo that carries with it exactly. I had an unofficial date - her date never showed up; we were friends at least, so that was ok. We did share at least one dance, if I recall right.
After graduation, we did have an all-night senior party at a tennis club then; the place was shut down otherwise. That was fun - good food, good music, great setting (LOTS of space), and it was only $10. Lots of prizes given out too for various events.