Whether the parks will close sooner, or later doesn't affect the crowd from what I've experienced. The weekend is the weekend. Regardless, it's going to be crowded more than the weekdays and will be more crowded depending on whether peak season, or not. I suggest if you're doing a weekday to stick with the beginning of the week. Most people who take vacation time off start towards the end of the week and typically are leaving, or already left by Sunday, or Monday.