Im not sure there is a perfect solution so Im not saying anything is right or wrong, but I make some observations based on comments from convention go-ers, and my wife who used to arrange conventions & conferences for a living.

Normally, 'workshops' would not be expected to be held while the bourse floor (ie the main attraction) is open. It would not be unusual to for more than one workshop to run at the same time, so guests have to make their choice, but Lori says that was always a more popular way of doing it than expecting people to give up 'browsing time'.
In our case of course, we cram so much into 4 days that it just does not leave us much time.

However, I do think the timings of the early morning slots should be looked at. Thursday a.m. this year for example, it would not have been unreasonable to expect 50 to 100 people to listen to David Schwartz. Instead, at 8.30am, we had 100 people with the required credentials to get into the show for the first hour lining up outside the bourse door, to make sure, for whatever reason , they beat the non-Riv residents in.
Given we had the early hour each day, that could well have contributed to people not attending the 8.30am workshops (added to the fact they are probably too early for many people)

The attraction of South Point, and the fact guests are less likely to leave the hotel as they would the Riv, could well give an increase in attendees without doing anything different at all.

Last point. Lori says it is not unusual to poll potential attendees on the subject material they would like to see at the workshops, rather than the club telling them.