Our dress code is:
NO SUITS (the people we work with often have enough suit wearers in their lives), although as the boss I do put one on if I have to meet funders, Government Office, Regional Development Agency types, etc.
Jeans are fine as long as they are clean and not too scruffy
T-shirts ditto and no offensive slogans
No visible underwear or cleavages
No shorts - whilst we are quite relaxed I don't want staff to look like they are going to the beach for the day