Depends. If it's busy, then you may have an issue doing the bigger attractions. I know that my dd and I did both parks last August. But, we didn't do everything....no Dueling Dragons or Hulk. We did buy the FoTL passes though. And when I was there for two days in Dec, I was more than ready to head back to WDW by noon on our second day. We got to the parks on Wednesday, by 8:30, and stayed in them until around 5ish. Then, headed back again first thing on Thursday morning. I was ready to leave but our Mears ride wasn't coming until 3ish. I really did everything I wanted to on that first day.