You get Reginald's Suit (Agatha's Dress for a female character) after completing the Trinity Tower quest near Diamond City. It's obviously a matter of opinion, but I really like the way it looks. It also grants +3 charisma, which is better than the clean black suit, clean gray suit, or whatever other color. I combine it with a trillby hat (another +2), which I really like (and can be given ballistic weave upgrade later on), and the fashionable sunglasses (another +1). That gives you a total of +5 charisma, and looks pretty good in my opinion. The glasses look kind of corny, but they're not that bad. I think this is the most you can boost your charisma with an outfit.
Here's Reginald's Suit - http://fallout.wikia.com/wiki/Reginald
There are a good number of them. The sequin dress and the red dress are the 'sixiest' dresses in the game I think. They both grant +2 charisma as well as I recall. I'm a male, so I don't wear them personally, but I haven them for Piper, Cait, and Curie. Agatha's Dress (+3 charisma) is a unique one that's basically a variant on the sequin dress and is awarded to female characters after completing the Trinity Tower mission, as I mentioned above.
I haven't seen any women's hats specifically, but overall there are a decent number of hat options in the game. I like the trillby hat and the newsboy cap personally.
Here's Agatha's Dress - http://fallout.wikia.com/wiki/Agatha