What in the world is wrong with having your own children at home with you two days a week? My two year old loves to help me clean! Give the little guy a rag and a spray bottle of water and let him go! You don't have to be fully focused on your two year old to have their time be well-sent.
He's not sitting at home "all day, every day." He goes to preschool, and he's only two. My two children, who are 3 and 8, have NEVER gone to a preschool and have spent EVERY day "at home with mom" and I could hardly call them unenriched, bored, or anything of the other nonsense. I have nothing against preschool, but you seem to think it's better than time spent with mom. NO time is better than time spent with mom when they are that young. It's fine to have preschool...plenty of good experiences there...but it doesn't have to be every day! To say that preschool is essentially more engaging to your child than YOU are...
There are plenty of great things you could be doing to engage your own children. Clean when they're sleeping.
**I'm adding a little more, because I agree with others that this post makes me sad. Do you know how enriching a trip to the grocery store can be? What a perfect opportunity for you to plunk your toddler in the cart, right in front of you, and TALK to him! Teach him colors and names of vegetables and fruits, let him put the apples in a bag, ask him what he'd like to buy, etc.
Errands can absolutely be enriching, if you aren't just dragging your children along. Engage them in it. Talk to them. Teach them. No, I probably wouldn't bring my children around to pay bills, but I certainly would bring them to the grocery store! How many other errands are there?
I just can't imagine putting a baby (15 months...talking about your youngest one) in what is essentially daycare just to have "me" time. They're only babies once. I get it, when you have to work...but if you don't? Someone else is not better than YOU are.
***Karen...AMEN! I feel like I should just leave this sentence and erase the rest of my answer.
**I also don't think "preschool" for a 15 month old or a 2 year old is in ANY WAY more enriching than spending time with Mom, even if it involved doing errands. I'm sorry, but my children have learned so much just by going to the grocery store! There are so many opportunities to use it as a lesson...not just about food, but cultures, numbers, letters, colors, everything! Sorry I keep drilling on this one point, but what do you think they do in preschool for a few hours every day? Maybe you should sit in on the class for a week straight, and see if you still find it totally engaging for your child.