Hey-oh! So what will happen for cosplay gatherings is they first open for the big groups (League of Legends, My Little Pony, Homestuck etc.) in February and then in March it will open for all groups.
Map of locations I see you already found! Should be very similar for next year (only possible change i could fathom is DT3 shifting, everything else is solid). As for spots, once Feb rolls around people will start to know what they want to cosplay so you'll know what sort of group you are expecting. Some spots are better for big groups and some are amazing for small groups. TCC1 is a really nice spot, but only works for smaller groups for example.