I have to agree with everyone and add that your MIL would go NUTS in my house. I clean while Luke is strapped in his highchair. Sometimes we'll have an unscheduled snack so that I can vacuum. I agree that independent play is so important. Tracy even mentions in her book that it's important from an early age. Another thing I want to add, and it's mentioned in a post somewhere on here, that we, as SAHMs, are showing our children how to "function" in a day to day life. I know working moms do too, but this was on a SAHM thread. Anyway, it's important for your lo to see you cleaning, saying thank you to people at the grocery store, taking time for you, etc....
You're doing GREAT!