I don't have toddlers anymore. I wish I knew everything I know now back when I did have toddlers though! So I'll answer a question I was asked about this in hopes that it can help. It's what I would have done, but I can't practice it so I don't know how worthwhile the information is!
The main thing that I would do with toddlers is that I would have clear "free time" and "family work" times. I would teach them what they are and what is expected out of the toddler when they are in that activity.
For family work time I would have them help me with all my household chores. This takes real discipline from mom. So you may have to work up to it! A three year old can learn to sort clothes, fill the washer and fold laundry with moms help. They can match socks and help put small piles of clothes away. A toddler can empty the silverware from the dishwasher. They can set the table for dinner. They can scrub a toilet and wash a wall. There really is endless things they can do side by side with mom.
By doing "real" family work and helping mom they gain great confidence in themselves and the vital aspect of self-worth within the family. They learn discipline and increased stamina. It is not work to them because they are with mom and they think it is fun. I did do this with my daughter and she learned to do all kinds of things as a toddler. She is well disciplined now and works hard. (Why I didn't do it with the rest of them I don't know).
The toddler will learn colors from sorting laundry, sorting and categorizing skills from silverware, basic math when setting the table, etc. If you spend time talking to them while you are working they can increase their vocabulary and verbal articulation skills. You can memorize many things together. Liberty learned the names of the 12 apostles at age two. You can sing primary songs. I would sing the Books of Scripture songs with them. They can learn anything. They will learn if we have the patience to teach them. Also they are tired when they are done! Toddlers need to get worn out so they will sleep well at night and nap time.
When mom needs to address Baby's needs she can then dismiss the child for "free time." The Toddler can learn that free time means "not bother mom time as well." In the beginning this might only last 30 minutes, but over time they can increase the length. They learn this is the time they get to play with their toys. They can build with blocks, play outside if the yard is fenced, or play with whatever "lifeless toys" you choose to have. (see the the Headgates article) I would help the child learn that they create their play and not have it dictated by hours of entertainment based toys and activities. Children need to learn to play by themselves and not be entertained. It is hard. It's so much easier to turn on Dora. Save Dora for emergencies. With discipline though there should be few emergencies.
I'm embarrassed to say that free time for my toddlers was pretty much ALL day. Free time included as many Blues Clues episodes as they wanted among other things. Also they had a whole play room full of push button, cartoon toys. They learned they wanted to be entertained. I am paying dearly for that now. I should have taught them that free time only happens for a couple of hours all day. If only I knew then what I know now!
Of course you'd have times where you would read and play games. And perhaps this time would be "mommy time." I would also take them outside as much as possible. This is vital. This also wears them ou. So when you have to be inside working on those things that can't involve the toddler they are willing to amuse themselves.
I would save the free time until you desperately need time for Baby or a shower or something. They will be trained that they need to amuse themselves and that they need to leave you alone. The discipline they are building is vital for when they are older and are trying to get through Shakespeare, Euclid and a host of other books and other physical and mental activities. Training is hard, but focusing on it now when they are two and three is so much better then when they are older. Trust me on this one!
So wear them out with work time so that when you need personal time they will be more than happy to run off and play by themselves.
If you have older children they can of course help with the toddler. They can do some mentoring of them also.
I highly recommend "Home Education" by Charlotte Mason which is volume 1 in her series, "The Original Home Schooling Series."
This is what I would do in hindsight and this is what I'm going to teach my daughter to do with her children. I hope the information is helpful. Please share your thoughts on activities with small children in applying these principles.