I'm pondering of going either tomorrow, Saturday, or on Monday. Are there any notable differences in crowds between weekdays and weekends? Weather seems a tad nicer on Monday, some rain possible tomorrow, but it might be that I'd be able to get there around lunchtime on Monday while tomorrow I could make it when the area opens.

Also, is the Expo worth it if I only go take a look at pavilions and exhibitions that do not require signing up etc.? Or how easy is it?
EDIT: Booked on Monday as it showed tomorrow first available entry time was at 5pm.