I can't really speak to what makes a good gaming convention as I've only attended 3 different named conventions. One of those conventions I've attended on multiple occasions although it has changed a bit each time I've gone. I know why I attend conventions but that's not the purpose of this post.
By asking the question "What do you want?" I'm aiming that at the convention organiser as opposed to the attendee. The attendee wants a lot of things from a convention and each different attendee will have different demands of that convention.
But what does a convention organiser want?
The organiser must create a balance between the number of events held to attract the attendees and in turn enough attendees to fill those events. This is very much a chicken and egg situation and is a core challenge for any convention organiser. For a new convention trying to determine attendees is nigh on impossible but to attract attendees you have to provide events attractive enough to well attract them.
The balance isn't a simple case of anticipating 100 attendees and having 100 spaces to play games. The various formats within the hobby bring complexity to the challenge of organising a convention as the mix of games on offer will influence the attendance.
For returning conventions the organiser needs to choose as to whether more of the same is the right option or whether they wish to grow. Which brings us to the next thing an organiser wants...
The organiser doesn't want to do this just the once. Well ok so they may want to do this once to prove that it can be done but doing something like this is rarely a once time deal. Usually this is something they want to do once a year and with each year they want to do it better than the one before.
To do this the organiser must be prepared for things to go wrong and ultimately for the convention to not meet the needs of the attendees.
However for everything that doesn't work there will be at least one thing that goes well and results in an opportunity to improve the convention for next time. A next time that will only happen with the next thing an organiser wants...
The organiser can't do it alone. They need support and that support will come in a variety of forms.
One of those will be financial whether that be from sponsors (if there are any) or simply a mechanism of spreading the financial risk of the event.
Another key element of support is in the actual running of the event and the organising that goes into making it a success. The day to day organising and prep for the event cannot be done by 1 person and somewhat more obviously the on the day running of the event cannot be done by 1 person. The organiser must have a team and that team will also need support as there will be a need for more than that core to ensure that everything runs as smoothly as possible.
What else does a convention organiser want?