March 4 -- my word, in my part of the country, we're still buried in snow on March 4!
Okay, I have a couple of thoughts. I speak as someone who went to a number of proms myself (back in the day), who watched my brother go to a million proms (he was sought-after as a prom date, year after year, in several towns near our own, it was like a sport for him) and who has now put a son through high school and observed all his formal occasions as well.
Here are my two cents.
Dresses can be girly (lacy, ruffly, sweet) or sleek. If you go for a dress, sleek will complement your physique more than girly will. You could also skip the dress entirely and do a funky version of a tux.
If you opt for a tux, skip the sleeveless styles that have been so popular for formal events over the past few years -- unless you're in a desert climate, it will be too chilly for them anyway -- and go for something with a bit of a sleeve, or a jacket over sleeveless, or a wrap over sleeveless, or a column dress with long sleeves. You're in fantastic shape and can wear something body con if you want, just don't do skin exposure AND body con. One or the other, not both.
You don't have to completely camouflage all that hard work you've done and your amazing muscle tone, you just don't want to be too "in your face" with your muscles or you may look like you're on your way to the gym. (I'm not suggesting that only girls should hide their muscles. Only girls show any skin at all at formal events, so it doesn't really come up for the guys, as long as they wear standard formal attire. When the guys start wearing gowns, we can talk about whether they should flaunt or soften the appearance of their muscular physiques.)
