I have just decided not to take on a part time job, after considering it seriously for a few days. I was offered a job teaching a language course for adults. I am a teacher by profession, so it's not totally out of my field. It would have been a two hour class, and I could have taught on Saturdays, while DH watched the kids.
The problem is that I would have been facing an hour-long commute each way, along with a 13 dollar train ticket. Plus I would want to be there early for prep time. For only two hours of work (and pay), I felt five hours of our family time was too much to offer, so I declined. DH was even willing to take the kids for that time (despite also feeling that the gains were not worth the costs), but left the decision up to me.
Not sure if I made the right decision, but because of this, DH has suggested that he takes the kids for a couple of hours on Saturdays so I can have some personal time. I will also be looking into other job possibilities, perhaps tutoring.
So yes, I can absolutely understand how a part time job would seem like a break, and I could see myself going down that road.