If you're looking for really fantastic ballroom dance shoes, Celebrity Dance Shoes are the best I've ever worn. I refuse to perform in any other shoes! They are more expensive than most--about $100 to $150 for a custom pair, but they are worth the price. You will not be disappointed! If we'll pay $750 for a costume we put on our bodies, why not pay a little extra to take good care of our feet, too? :)
The insoles on Celebrity dance shoes have very cushy foam padding--it's like dancing on a cloud. The buckles that hold the straps on are actually snaps in disguise, but they just look just like buckles! That makes them as adjustable as you need them to be, since you can slide the buckle up and down the strap to adjust for a perfect fit. And since they have a snap instead of a buckle, you can get them on and off in a hurry.
Also, the entire inside of the shoe is lined in leather or suede, which makes them very comfortable to wear. No ragged surfaces or rubbing!
You can custom order any of their shoes in any of their fabrics (they have metallics and glitter and holographic stuff...lots of sparkle!), and for many of the styles you can choose what height and style of heel you want on it--anything from a flat to a 3" heel.
For closed-toed styles, order your regular dress shoe size. For open-toed styles, order a half size down from your regular dress shoe size, since it's desirable to have your toes hang just a tiny bit over the edge.
http://www.celebritydanceshoes.com
Their website is a little primitive, but you can request a paper catalog, which has very nice color pictures in it.
Forgive me if you already know this, but one thing to remember with any suede-soled ballroom dance shoe is to take care of the soles. Don't wear them outdoors or dance on wet surfaces, because that will ruin the suede.
As for what colors to get, I recommend getting two pairs: an all silver pair, and an all gold pair. That's all you really need to go with any costume you have.