Do you have a lot of dual purpose furniture, like an ottoman that has storage inside or end tables with drawers? A hidden away space to toss all the toys? Make sure you have few enough toys or large enough storage that everything can be stashed away, no overflow. That can help to make "straightening up" quick and easy. I do my best to keep the kitchen and living room (rooms that can be seen from the door) in a presentable condition, not super clean, but not embarrassingly disastrous. The rest can be shut behind closed doors for unexpected company.
But most importantly try reading "Song for a Fifth Child" whenever you have an urge to clean. Accept that this is the hardest time (in terms of your kids' ages) to keep the house cleaned, and any mother will know this and sympathize. You just have to give yourself permission to enjoy your babies (or rest so you can enjoy them later), you will never get this time back, but your house will be clean eventually. In fact I just framed this poem for my friend's baby shower because it beautifully sums up my most important mothering advice.
Song for a Fifth Child
by Ruth Hulburt Hamilton
Mother, oh Mother, come shake out your cloth,
Empty the dustpan, poison the moth,
Hang out the washing and butter the bread,
Sew on a button and make up a bed.
Where is the mother whose house is so shocking?
She’s up in the nursery, blissfully rocking.
Oh, I’ve grown shiftless as Little Boy Blue
(Lullaby, rockaby, lullaby loo).
Dishes are waiting and bills are past due
(Pat-a-cake, darling, and peek, peekaboo).
The shopping’s not done and there’s nothing for stew
And out in the yard there’s a hullabaloo
But I’m playing Kanga and this is my Roo.
Look! Aren’t her eyes the most wonderful hue?
(Lullaby, rockaby, lullaby loo).
The cleaning and scrubbing will wait till tomorrow,
For children grow up, as I’ve learned to my sorrow.
So quiet down, cobwebs. Dust go to sleep.
I’m rocking my baby and babies don’t keep.