I do know couples who did nothing but eat, then crash after their fancy and stressful weddings!
I'll give them the advice my dad gave me... Get out of the reception as soon as you possibly can! They'll have a fine party without you and you will be more exhausted than you think. Find someplace to have a terrific meal, and de-stress a bit, then do what you want :~)
Hair's dad sure was right about that. After about 20 minutes of receptioning, I just wanted out of there.
You might want to plan on getting something to eat, too. We were far too busy meeting and greeting to eat anything at the reception. After we left, we went out for steak and lobster and pints, checked into our room, and had an enjoyable afternoon. :)