The discos have a cover charge later at night. It's a good idea to get there early. When the parks close, everyone is walking thru CityWalk. Happy hour for most restaurants ends at 7pm.
If the parks close at 7pm, I'd head that way around 05:30pm.
After 6pm there's no fee. I went with this one girl earlier this year to HRC shortly after 6pm and not only was there no fee. but we only had to wait 5 minutes before getting seated. The parks closed at 7 that night, so when we left, there was a healthy wait.
Also, if you're visiting the parks and have the time, go to CW for lunch. Most of the restraunts will have little waiting time before getting seated. I went on Sunday and was seated immediatley at NBA City. When leaving, there was about a 10 min wait to be seated.