Hi A.,
I was also a very busy Mom when my kids were growing up. I had times that were family time and then we had cupboards that had projects for them to do. It contained Playdo(sp), puzzles, crayolas,books and it changed with their ages. As our daughter got older she loved to make jewelry so we would make bead buying trips for her to choose new beads. It is very important that they are able to entertain themselves too.
Our son loved to invent things so we had odd and end things in a box for him. They would be old spoons,broken things that were safe for him to use.He would spend hours making new and wonderful things.
Art projects are wonderful. Older children love to glue and paste or create an album. You can be as involved as you would like to but be sure and allow them to use their emagination.I would hold and help do the gluing for my younger child so he could glue like his older sister. Baby wipes or wet wash rags were great to have on hand for sticky fingers.
When they were a little older they would spend an entire day writing a play and planning wardrobe to be put on for us after dinner. Girls love dress up have a trunk of dress up clothes for them. We took cardboard boxes and paint and crayons and made a kitchen. Later we were able to afford a play kitchen with little boxes of food.
We had a rule that everything was to be put away before another project was taken out. This was hard at first until they realized that after one reminder to put away and it did not happen it would disappear. I had a box where things would get put and get put in the can not play with cupboard. It would stay in that cupboard a little longer each time. Then they would get it back and we would talk about it. They got it and would put things away most of the time with only a few slips.
The girls can help you make meals. For lunch I would set out peanut butter and various toppings for them to make their own sandwiches. They loved to help clean up too as we made a game out of it and we all did it together. We did picnics and trips to the local park on nice days. They loved helping select what we would pack and packing.
Playtimes with friends are wonderful and give you some time. If your friends have children about the same age set up play dates and trade off on where it will be. Time to do you things( like a long bubble bath) Hire a girl to come in and play with the girls while you have you time. I felt wonderful and my husband noticed and loved it when I did the me time. I even took a nap one day and was a new and better Mom. Our entire family benefits as when Mom is happy everyone is. The kids have fun and so does Mom.
On rainy days we may go to the movie store and get a movie to curl up and watch with our popcorn
We had set times for naps or quiet time when they were older. They could sit and read a book or color. This was usually set at nap time if we had a little one who napped.
There are many more things that can be done but these are just a few. Hope it helps