Doesn't a sleeping baby like this make you want to close your eyes yourself? :) I am a firm believer in nap-time for children, so all three of my kids take good afternoon naps (Noah still takes a morning nap too, and sometimes an 'evening nap', and probably will for a long time). They all lay down between 1:30 and 2:00. Cosette usually sleeps for about an hour and a half, and the little guys sleep for at least two hours. This makes them so much more pleasant and obedient when they are awake; I notice that when they have to skip their nap, they are so much quicker to fight and argue, or be disobedient to me.It's also a HUGE blessing to me to have a couple of hours in the afternoon to myself :) So, I encourage you to take those cranky kiddos and lay them down for a nap.....you'll be so glad you did!
Oh, and if they think they are too old to need an actual 'nap', or they're not used to taking naps, try laying them down with some library books and saying 'You may get up when the timer goes off in 25 minutes', and gradually increasing the time. You may find that when the timer does go off, they're sound asleep! Cosette often does this if we're at my mom's house in the afternoon. I will get her all snuggly in the big recliner in their living room with some books, and before long, she's out of it.
There are occasional days when it's difficult--maybe Eli doesn't 'want' to nap that day, or Cosette is distracted by noise outside her window or something, but we work through those days, and in the end, it's well worth the effort!