My girlfriend occasionally goes braless in public and is almost always braless at home. In my opinion, she is the perfect size... not too big that she is uncomfortable without a bra, but small enough that they are perky and look great in a top without one on.
I'd have to say my favorite situation is one that just happened... she sent me a little tease video before going out of her getting ready, including pulling a sundress over her head and pulling it up to show she had nothing on under it. When it was time to leave, she walked out in the same dress. She teased me all night, and I'm sure a few others while we were out. Hard nipples in a sundress looked pretty amazing to me