We changed our tryout structure years ago. Because we don't change the roster over each year we are able to do it this way. Maybe it doesn't work for everyone - but it does for us and personally I would like it this way if I was a players parent.
* We don't have open tryouts. Contacts must be made in advance of the workout. If we don't know the player or can't get information about them in advance we will take an hour to work them out individually sometime before the tryout date.
* Our tryouts are done exactly like your practices. They might run a little longer because of the additional players. We break everything, every skill down in 10-15 minute intervals. Everything is preplanned and on laminated (best investment we have made) sheets for all the coaches. One parent keeps us on time. In our mind we run practices better than most teams and we want the players and families to understand what will be expected of them if they make the team.
* Families know everything in advance - team costs, practices, potential schedule, home work expectations, conduct guidelines, etc. No surprizes for the families and no drama allowed after the fact.
* All players must attend - whether current teammates or potential players. Team chemistry is critical. We all spend so much time together everyone needs to understand the team makeup before making decisions.
Like I said - after seeing and doing many different tryouts over the years this works for us.