@Sarah Montgomery, Shaun, is generally accurate, but I'd like to add a bit more color here. 

What do you guys generally use for floors, counters, paint colors, etc... 

We've struggled with many of the considerations you raised above and I'd be willing to provide additional color to what's been outlined above based on our experience in TX.

And usually one color is on sale.

I need the recipient to open the letter, so I use a really good handwritten font and will also change up the color of my envelopes from time to time. 2.

I'm in Miami as well (Coral Gables specifically).

I have a quick question in regards to the opinion of rehabbing my second rental property and have a question regarding a decision of cabinet colors, should I paint them White or Brown? 

I think that Menards calls it citadel, and another color is Java Teak.

I'm not a whole seller so hopefully one of them will tell you what method works best for mailing but i would think, hand written on a color other than white to stand out would be the way to go.  

I guess there are statement colors that could work against wood like driftwood but I never tried it.