C.M.
Set up scheduled time for activities. 1 hour for free play - you playing with them then go to the 'bathroom' and see how long they play alone. Then come back and switch out toys, go check on the 'laundry', etc. This will teach them to play on their own.
Set up time to play in the kitchen (while you clean, cook, etc). This can be with playdo, shaving cream, utensils, toys in their high chair/booster, etc.
Set up a time for snack time. Could be something they can play with too like fruit loops, m& ms, cheerios and ask them to put all the cheerios in a bowl, all the m&ms in a bowl, etc.
Set up reading time where you sit with them - could be 5 or 50 minutes depending on their attention span. My daughter from age 1-2 wanted to listen to/have us read her books for like an hour each morning and before bed!
Outside time - even if it's cold...as long as it's not freezing, icy or dangerous to be outside. Run around, scaveneger hunt, pick up sticks in the yard, leaves, etc.
"Out of the house" time - McDonalds playplace, Bounce U or Monkey Joes, free activites at a library, Home Depot, etc.
I find if you try to structure the time then it seems to go by faster and it keeps them busy and they do not get as bored!