After further research it appears that there must be something going on during this time as there are no rooms available at many downtown hotels. Bummer :)
I bid beginning at $60 going up to $80 adding a zone each time. No success and no offers. I'm out of zones to bid which do not contain a 4* hotel. :) edit: sorry, dates were 5/15-5/17. $60 $63 $66 $68 $69 $70 $71 $73 $76 $80