What kind of meeting? What is your role? If you are there as an attorney, I would wear a suit and heels. If you are there as a client, I think you can wear about whatever you want, including riding boots.
I'm not an attorney but will be there supporting a specialized expert witness who has been hired to testify on behalf of the firm's client (litigation related).
In this case, I think a dress, blazer, and boots is fine.