I have a pair of Doc Marten Smith 4 ties that I wear just about everyday. They also come in a 5 tie boot version.
Square toes are definitely out right now but this sort of tapered to a square are still in.
The cross between a trainer and a dress shoe that others have posted above are great too. It all depends on what your style is.
You can wear pretty much anything these days but you need to have the attitude to pull it off. Like dogs can smell fear... people can sense when you are not comfortable in your clothes.