@Dani Murray - Welcome to the Community!

I’m investigating Miro for the company I work for and wondering which plan to go with.  We would like to use it to run workshops

The Starter Plan would work for this purpose, as it supports editing by Visitors, which is where the board participants would not need a Miro account to access and edit objects on the board, e.g., sticky notes.

“Guests” is a slightly different feature where the participant would need to have a Miro account - even a free account is fine. The Guests feature lets you

• give non-team members different access, e.g., one of the guests needs to edit, while another only needs to add comments.
• the board can only be accessed by those you explicitly add to the board, as opposed to the the board being set to “Anyone with the link”, i.e., Visitors access and someone with the link ends up sharing it (unintentionally or not) with people whom you do not want on the board.

The Guests feature is only available for the Business and Enterprise plans. There are other benefits to having a Business Plan subscription.

To learn more about the difference between members, guests, and visitors, read this article:

https://help.miro.com/hc/en-us/articles/7045408248594-Visitors-guests-and-members

And for plan comparison, this: https://help.miro.com/hc/en-us/articles/360017730233-Plans-and-features-available