Agree with PP, you give them a heck of a deal on child care, hopefully they don't expect the going rate for dog sitting. When we hire a professional, it's about $30 a day for two dogs, two visits a day.
When BIL does it, we buy him a case of beer and return the favor when he's out of town.
Maybe pay them $50-$75 or a gift card to a nice restaurant for their help?
We pay $15 a day to board our small dog with our vet. I would say pet sitting was worth about that per dog. I think trading daycare services would be a good idea in your case.
Could you do a trade? Offer 2 free weeks of the morning/afterschool care (given the fact that they are coming three times a day for a week, I think two weeks is reasonable).
I am a little sad to hear of people being gone for ten nights and having their dogs let out twice a day. We have a niece that will be here in our home for the 15 nights we'll be Disney. She will receive $450 in cash plus a $50 gas card, $50 Whole Foods card, $50 chipotle gift card and a $50 Office Depot card. Loving our dog and cat as we do is important to us and we feel this is fair pay.

Meh, our dog only goes out 2-3 times a day when we're home. This Winter, she refused to pee for almost 2 days when it was super cold![]()