DH and I went to Las Vegas last summer while the kids were at their grandparent's house for a week (they live 3 hours from us) and while we were in Vegas, we decided to head over to
Disneyland for the day. It was awesome, we got up really early and was able to get into the park by 10:30am, we spent some of the morning in California Adventure and then hopped over to Disneyland park for the rest of the day and into the night. We did spend the night and headed back to Las Vegas for the rest of our stay there. On the flip side it was just DH and I so it was very doable, but then again even if the kids were with us, I don't think we would hesitate to do it again.