Should you wear anything beneath the suit?
Airing out a suit and letting it rest is a crucial step many people skip, but if you adhere to this policy, you'll increase the life of your dress clothing whether or not you wear underwear.
And as to the fact that the fabric is lighter and drape, that's certainly true, but it really depends on the suit how much shows. Dark colors are good choices, in general, but the fit is crucial, and the only way you're going to know how the suit falls is to try it on how you plan to wear it. If anything, the amount that shows is likely similar to someone wearing boxers.
Some people may be wondering should you wear underwear underneath your formal wear?
Going commando in a suit pant would welcome many problems like chafing, ruining the suit, looks unprofessional and sometimes, the urine stain would be visible which in turn is very bad for your reputation. If I was getting sweaty in my suit regularly, it might be better to have some absorbent layer between me and the pants, but otherwise, why bother?