All of the above!! If you are attending more than one day you can certainly bring multiple cosplays depending on what you can pull together. The Great Saiyaman would be fun. And it seems like all the Batman Beyond fans are coming out of the woodwork lately so it would be awesome to see a Terry McGinnis (*huge BB fan here*).
Random Thought: Based on you second photo, you could pull off an observer from Fringe rather easily. Just a suit and hat, maybe a briefcase. Though that might be a little freaky to see too, especially if you can do the monotone voice, lol.