Routinely, I choose an outfit the night before and hang it on a hook over my door. It's a good idea to have a suit on hand for conferences and workshops. It also comes in handy if you are in the market for a new job. Ladies, a nice dress and jacket will also work. Pantsuits may also be appropriate depending on the company and the nature of the work.
Good colors are black, navy, or tan.
Shoes should be clean and polished. Lands End has a great Web site to help you coordinate a look that's just right for you. It's fun and gives you ideas you may not have considered trying before. The model is very realistic and rotates 360 degrees. You can build a quick start model which represents your basic shape or you can create a detailed model using your measurements, that will model your exact size.