We usually don't arrive til late afternoon or evening. I think only 1 time out of 15 (our honeymoon) did we ever go into the park the same day we got there. We just prefer to check in, check out the resort and get rested up before we hit the parks the next morning.
In '06, we went to Vegas for dh 30's birthday. We live in Maine, so we figured we weren't going to go all the way out there and not make a trip to Disneyland. We spent a few nights in Vegas before flying to CA. Of course, we couldn't leave the slots until 2 am, got to sleep at like 3, alarm went off at 3:30 so we could get ready and make our 6 am flight. It was only like an hr flight, but by the time we got to the Disneyland Grand Californian Hotel, no rooms were ready yet (it was like 9 am). We gave them our luggage and although completely exhausted, we hit the parks. It was also in the middle of August, so extremely hot too! I had never been there, so we waited in lines for like 2 hrs sometimes. It was horrible. Not to mention we were both completely exhausted and not in the best of moods. We decided to head back around 2 or 3 to see if anything was available yet. Our room was ready, so to bed we went. We had planned on getting back up at 8 and hitting the parks again. Well, alarm went off and neither of us wanted to go out again. After a few mins laying in the dark, one of us spoke up and said we were starved. Got one of the best room service meals before crashing again. Thank God the next day we were much better and well rested. Had a great trip there before flying back to Vegas for a few more days. Had the best time of our lives that trip! Of course, this was all before we had kids too!