To me one of the great things about Vegas is you can see beautiful women in sun/summer dresses 9 months out of the year. IMO those don't have to be short to turn heads. And if it works with the skin tone gotta love pink as a color.

I recently purchased a bright yellow dress (I usually wear black as I don't like to attract attention) and it has been a huge hit with anyone who's seen it

Tree stumps like legs, then a long dress. But you need to consider day or evening, hot or cold...way too many variable..I hate to make this sound like I'm circumcising a mosquito but....

... looks good on the floor!  Hey-oh!  Sorry, low hanging fruit, couldn't resist.

Obviously I'm partial to any dress with a leather or fetish flair, but I'm a one-off.

I think the fit of the dress that alludes to the body under it is probably more engaging for men (we're all stupidly visual creatures.)  The length really is dictated by the occasion.  And there isn't much of an occasion to wear a floor length dress outside of gown anymore is there?

It depends on the occasion and the particular lady.  Although in general, sun dresses are nice, especially in Vegas where the temps are rather warm.  Long dresses are usually more formal, so they would look nice when going out to a fancy restaurant for dinner and/or show.  I also like mini-skirts which dates back to the '60-'70 era.

As for colors, I've always like a little red or black dress (short) on a lady.

....... skirt with a split that shows off the legs intermittently.  Just a delicious tease of thigh.  The guess of whether the lady is commando.  

The color is personal.  

Damn, got me all worked up.

If her legs are nice then above the knee loose fitting dress is a must.

A short cocktail dress is always nice but depending on the occasion or location a long dress with pershaps a slit along the leg is very sexy.

The color always depends upon the lady.  Showing off her tan?, the color of her eyes or hair.    

What's your preference and why?