The fun thing about being single...hmm...well, I would hope that if I have a partner (one day) they could be comfortable with me just fully being myself (as I am single) enough that things would be alright...but that aside:
Being able to sleep, be awake, be loud, have silence, eat, or otherwise do whatever you want whenever you want (within reason) with no one to answer to or interject.
You can also look, smell, be, etc however you want (if not around people) with no worry or care about what others thought or saw. (Being naked if you so choose...for example...or having a day or two off when you do absolutely nothing)
Other than that, I'm sure there are some cool benefits, but being with someone is really great, too. Believe me, regardless of what people try to impress, they both have GOOD and BAD parts to them CONSTANTLY and inconsistently as well. ^^0 You just have to learn to accept and dare I say enjoy...both.