I'm very lucky in this department. My MIL is wonderful!
She's completely supportive of our parenting choices, or at least she knows how to hold her tongue, as she never second-guesses or criticizes us.
She checks with us before buying anything for our DCs because she knows we have preferences and opinions about the toys and other kids' gear we want to have in our house.
She lives nearby and is more than happy to babysit when we ask. Evenings or sick days -- she's a great back up.
She loves our kids!! She loves them when they're healthy and happy, and she loves them when they're puking and snotty and melting down because they missed a nap.