Bruce, if you don't get into an event, don't loose hope, as you can register for generic tickets and sit in on events sometimes. Generic tickets are for drop-ins essentially; if you see a game going on and it looks interesting and the next session they have open slots due to not being fully registered or if people don't show up who are registered.
As an example I ran 6 scheduled events last year for RMU, and all of them initially sold out. Actually there were only two of us last year that submitted events and mine were the only ones accepted due to the other submissions needing additional equipment and internet access (thus GenCon didn't accept his submissions for some reason, not sure if they didn't have enough of such capabilities available or what).
However it ended up that the first event, only one person actually showed up for (2 people cancelled after registering and others just never showed up), while 4 of the other 5 events, only had 4-5 people show up. There was only one of the six event I ran that everyone who was registered (6 slots) actually showed up for. As it was I allowed others to sit in if not everyone showed up, so with that 5 of the 6 ended up being full and that one at least had two people (as the guy who's submissions were not accepted sat in on that session. This was due to drop-ins with or without generic tickets. But having a generic ticket, helps increase the chances of being able to sit-in as it can at least the person running the event can help cover a portion of their attendance costs.
As such, it would probably be worth getting some generic tickets and stopping by just before the start of events that you are interested in if you can not get registered for that particular event, as openings may occur after the fact.
I went ahead and turned in submissions for 6 events again this year (even though I'm not absolutely positive that I'll be attending yet). But I submitted them late due to not hearing a definite result about ICE's backing until only a few hours before the first deadline for submissions and not having enough time to get it submitted by then. As such I'm not sure if the events I submitted will be accepted (although I did schedule them much later, so hoping that they will be accepted).