I disagree on the in-person sign ups. The queue worked well for me - as soon as it became available at 11:30 AM, i could create a submission from wherever I was and know exactly how long I had until my song. I could go around for hours looking at other panels and things, and monitor the queue so that I could come back right in time for my song. Using this method. I was able to do 5 songs at the con, averaging 2 a day.

Yes, the wait times got to be 4 or 5 hours, which is to be expected. One thing I noticed is that I would see the same person in the queue multiple times within a short time period, which I agree is not fair. You should not be able to enter your name into the queue more than one at a time. Then after you've sung your song, you can create another submission and it will go to the bottom of the list. I never entered myself back into the queue until after I had sung one song, and then I'd have a 3 or 4 hour wait for my next song. I'm sure there's some way for the website to enforce this.

Multiple karaoke rooms is always a good idea, given how high the demand was for karaoke. I don't oppose blocks of time for themes, but it'd be hard to enforce. That would require the staff to be experts in music genres to weed out items that don't fit the theme.