Often it was looking at the top industry publications and looking at the demographics of their attendees. Then, taking that to Sales for feedback as opposed to an open ask. Additionally spoke to industry analysts where we had a paid relationship to get any insights they had or which ones they prioritized. Those were added to the list of recommendations that were provided to sales. And, any new folks in sales that came from competitors, tried to get the top ones they went to at their past company that they found to be most valuable in terms of leads to closed won during a meet & greet discussion. New folks in the door are often eager to share from their knowledge. And, as a last resort, scheduled 1:1's with friendlies and got their input. Net-net, it's easier to have them react to a list and say which of their customers have attended which to their awareness. That's at least how I've done it and you'll not get 100% but likely will get the biggest ones to prioritize.
