Allow a node to have many dates attached to it
Just answering this myself so it doesn't count towards the unanswered total.

Turns out the answer is relatively simple - as long as you don't choose a Widget for the Date field that handles repeating dates, the 'Number of Values' field appears and you can choose 'Unlimited'.

So choosing either of the following Widget types:


Select List with Repeat options; or
Text Field with Date Pop-up and Repeat options


will not allow you to have multiple values. Any other options should be OK.