I am often asked about colors in the corporate work enviroment. I always steer people away from black as it is so harsh and generally does not promote conversation. Navy and grey are much better choices in suits for both men and women. While Navy projects authority, grey is a better choice when meeting clients or for sensitve meetings with employees. Keep the grey tone medium or dark grey as lighter grey never looks expensive.
This is an important question as more and more companies are looking for you to represent them in the best light. Here is my humble opinion. Jeans are fine if they are allowed, however, no matter what jean fashion maybe at the time, here are some rules to live by. Jeans need to be clean and in good repair. Do not wear ones with big rips and tears, patching, paint spatters etc, unless you work in an extremely creative enviroment. Your jeans should be a dark wash, keep in mind the length and the attitude you are conveying. Wear a belt if there are loops, otherwise it looks sloppy and not put together. Wear a really great pair of shoes to off set the casualness of the jeans. Make sure they fit you like a glove but not too tight. They should not gap in the back when you are sitting at your desk or at lunch.