I get a few hours after they're in bed and before I go to bed in which to cram cleanup, catching up with my wife, and other bits of essential life maintenance.
It does get easier as they age. Our youngest is three, so I have a while before the "hanging off my legs" phase is done, but I can remember the era of newborns, when I could be interrupted at any moment, and I couldn't count on an entire hour to myself at any point during the day or night.
(FWIW, a big part of making this work is shifting your mindset to appreciate the little things and recognize how precious they actually are. At this point I cherish being woken up by a wailing toddler and rocking her back to sleep, because I know I won't get many more moments in my life when she's a tiny little bundle snuggled up and cozy against my chest, and it's truly magical when I manage not to be hung up on anger over being woken up at 3 AM.)
- Parent of a 2,4,6, and 8 year old
My kids are 18 and 14, and I've done my best to encourage creating things instead of consuming things.. but sometimes they need some down-time, and so do I.
It's going to be harder to keep these boundaries as your daughters grow older and their natural personalities develop. They'll likely take interest in whatever their friends and social peers are doing, and the two of them may go off in wildly different directions. Stay engaged and be ready to adjust your parenting techniques as the girls grow older.