We lucked out on Splash. After riding Mansion and Pirates, we returned for Splash, only to find the ride down. (Apparently it went down right after I picked up the FPs.) But it came back up just as we arrived, only to go back down just as we exited.
I'm telling you: the theme park karma gods reward you for following the four-hour time limit. ;-)
And I think that one of the keys to maintaining a relaxed pace is trying not to do everything but only to do the very best experiences.
That's what I'm really trying to nudge people to do with the four-hour time limit. Cut out the second-tier stuff, stick to the best experiences, enjoy them, then move on to other top-notch experiences for a while (a great sit-down meal, time with the kids in a fun pool, heck, a well-deserved nap). Then come back to the park, later, for other top-notch attractions that you missed, or want to do again.
We have a version of the four hour rule, but not quite the same. Usually on a trip, we can spend a full first day together, and a second day, too, without getting cranky. On the third/fourth day and on, we make sure to set some time (not 6 hours, but maybe 3-5) aside to go have a quick nap, a swim, and a few martinis/beers back in the room when the sun is setting. It's really great, and if your resort has a balcony it can be as nice as anything the parks have to offer.
Then we're ready to go back to the parks. We're rested, fed (lightly), and ready to go see the good stuff with no lines. We catch the fireworks (if available) and have a late dinner when the restaurants aren't packed with hyper tourists.
Additionally, about three quarters of the way through the vacation, we plan on a slow day. No theme parks, so maybe we'll go to a water park for a while, then go out to Downtown Disney, CityWalk, or the equivalent.
And if at any time during the vacation I feel a little tired, bored, or cranky, or notice that someone else is, I go back to the resort. 3 hours is usually sufficient, and then we're ready to go.
The only real rule I do have for the family when it comes to Disney parks is that we get to the parks very early (usually 30 - 40 minutes before the park opens). It seems like we can get all the major attractions completed by about 11 - 11:30, then relax the rest of the day when the heat and crowds hit.
Probably the best time we had was when we stayed on property at the Royal Pacific Resort (Universal, Orlando). With Citywalk and both theme parks within easy walking distance, automatic fastpasses due to being on property, and almost a whole week to explore, we were very leisurely explorers. We never toured for more than a few hours at a time, and did plenty of resting a relaxing at the pool. It honestly felt like a real vacation and not a race!
But we have done the full day pushes, and as long as we have a good plan that doesn't involve a lot of back tracking, we can usually keep the family pretty focused and happy. Or, at least, we've been very lucky so far!
And, I, too use the 4 hour rule for the big rides. Get them out of the way, fast, then slow the pace way down for the rest of the day. I warn people when I take them to parks with me that I'm going to guide them through a fast pace for the first several hours to get on the big-line rides, then I slow them down. Since I've pre-warned them, they're usually quite happy and feel they got a really good day's worth of the park.
As stated above, the best is staying for several days and taking your time. Universal Orlando is the absolute best for this!
However, I think the 4 hour time limit can be flexible depending on who you're with. If it's with family, then I definitely agree that 4 hours is a great thing.
However, if I'm with the significant other and/or with another couple, we usually take a different route. We break the day up by riding a few attractions, getting a snack and hanging out, then going on a few more, eating at one of the sit-down service restaurants, then repeating. The breaks truly help. The biggest thing with this kind of plan is that the chemistry and energy with all four people has to be great.
After our evening break we usually go on rides for a second and sometimes a third time. I know a lot of how we are able to do this is our age. We are both under 30 and have no kids. Also think that part if comes from how park visits went when I was kid. The pace was a little more relaxed, but we would still usually stay open to close. If we were with friends we would probably do a 2 hour morning rush and then take the rest of the day easy and let them decide how they wanted the rest of the day to go.
Even now with a toddler and annual passes, we always stay longer than planned. It's just so hard to leave, unless the park is kicking us out.
However, I'll keep your four hour rule in mind for any time we might go with people from outside our family! I guess we may be a bit abnormal.
I get a limitied time for vacations and the closest theme park to me is 2100 miles away (Sea World San Diego). I make it count.
This year I plan on going to Disneyland, DCA, Knotts and Magic Mountain in October. We will have 4 1/2 days to enjoy our vacation. We stay in the parks for at least 8+ hours. We do have a long lunch and snack threwout the day, can you say churro? Just take your time and don't run to anything.