On the responses page, Meet-O-Matic indicates the best dates at the bottom of the response table in a row labelled 'Rank'. It also provides a 'VIP?' (Very Important Person) check-box option so that the proposer can refresh the best date analysis after indicating specific VIPs (i.e. those who really need to be at the meeting).
Just select the box next to the relevant names, and then press the 'Refresh best dates' button at the bottom of the page. You can specify how many of the best N dates you want rank-ordered at the bottom of the table (e.g. specifying 4 will tell Meet-O-Matic to indicate the rank orderings for the best 4 dates).