Dimples,
I had the choice of clear uppers or all metal. When the ortho said "no additinal cost because I am an adult" then I say HEY why not.
But the real issue wouldnt be color ligs, but how comfortable you are with braces which goes back to the question you asked about discreetion. Like many who has posted to this particular thread, they started out with clear for the discreetion, but realized that the braced look was more important to them than to someone else. If you feel that you can get the same effect from metal brackets that you can get in clear, then why spend the extra money. Now I was fortunate that my ortho doesnt require extra fees for your choice of clear uppers vs metal lowers, but if I had the choice I would still go with clear uppers. The reason why I personally chose them was not because of the look ( because I never cared what people said about me in the first place

) but because I dont need as much aligning on my upper as I did my lower. What I mean by that is that my upper arch only needs to have gaps closed. My lower arch would need to be shifted from left to right to match my upper midline. The ortho suggested the clear at no charge but preferred metal on the lower, he said that clear bottoms would take to long to close up extraction gaps.
To sum it all up in a nutshell, if you really want to be 100% discreet then invisilgn ( if you are a canidate) would be the way to go. With the clear vs metal discussion for the fancy lig colors, treatment time would determine which way I would go before colors, but clear does look good with pink

Remember that this is something that you would have in YOUR mouth for 18-24 months or longer. Also consider how it would affect your total treatment time. Why drive an oldsmobile when you can have a cadillac

Good luck on whichever you choose.
http://www.alstonortho.com/colorplanner.asp
Play with the colors and see what you would like to start off with.