Random thoughts....
The bases loaded format is about 25% really cool and 75% totally annoying.
Cal vs. A&M going to game three. Classic so far.
UCLA vs. MD very compelling too.
Really odd to see how some venues are jammed and some are almost empty. Kind of like MLB that way, and sometimes really mysterious. You get the feeling that everybody in Texas loves going to baseball games, except Houston, where they apparently have other things to do.
As far as fans in the stands I think it was who is playing. What I saw in Illinois this weekend was when 2 of other 3 wher playing you had those followers (maybe 75-120 for each team) and maybe couple hundred Illinois fans that purchased tickets for all games. (there was one game between Wright State and Ohio that probably had 400 fans in stands but announced attendance was 1400- my guess is those that had prepaid just didn't come because it was cold). When WSU played Illinois it was packed and that was Monday at 2pm. When ND played Illinois Sunday afternoon it was a complete sell out.
so in answer to your question, I think it is who is playing and that is reason for having top seeds host versus going to neutral sites for all.