Mine tend to sleep a lot during the day. It's an indication that your two are happy and content. This is why people think their dogs do the same when they are not home, which is more often than not, NOT the case. I left a tape on at one point, to listen to what was going on when we went out. You'd be amazed at all the coming and going, the pacing and the other noises we heard. When the leader of the pack is home, all's well with the world. I'd bet they are up and active when you do interact with them eh.
When to walk them is up to you - just avoid the heat of the day when it's hot (early morning and late evening would be best), and don't exercise for 2 hours after feeding, and don't feed for an hour after coming back from exercise. Work their walk-time around this and you'll be fine. I would suggest that you start your day by attending to their needs first, if possible. That way you can relax and get on with your own schedule. But then, I pander to my lot!! lol