We basically decide to skip the parades to take the break, it's well worth it. With one exception - in 2007, we did RD at MK, took a break for a CM brunch and then DD and I headed back to the MK to see some Princesses and see the parade, we headed back to the Poly the instant the parade was over, so she still got to take a nap. DH and DS had gone back to the Poly to swim after CM. We didn't have a TS dinner scheduled that day, since we did the brunch, so it worked out just fine. We ended up doing CS at Captain Cook's I think, and just hung out at the Poly. So it worked well - because we didn't have big evening plans.
DD and I are hoping to see the MK parade again this year - on the day we have our CRT lunch scheduled. Again, DS and DH will probably go back to the Poly after their CS lunch, and we'll stay. We DO have a dinner ressie - at the T-Rex, but I made that for 6:30, so as long as we get back to the Poly by 3:45/4, she can still nap for almost 2 hours. We have our car, so we'll be driving to DTD.
I don't think there's any way to see all the afternoon parades, take a decent break, and still have an early/reasonable dinner. But it's possible to make it work for a day if you want.