We do a mix. DH is full-time and I work 4 days per week, except over EFY, which means I work all I can.

Vacation care is the first choice,
then DH or myself taking a some time. During the shorter holidays I may take a couple of days and same with DH (thankfully he has RDO's)
then Friends. Some friends are happy to take the girls for a day. Sometimes I help them out as well. Often they are happy to have the extras around as it keeps their own kids from getting bored
Family. When possible MIL will come over (she is in Tas). Very handy over EFY as it means I can work more hours, also she helps with a lot of the housework, so really takes the pressure off there. Downside is that MIL is reluctant to drive now, so it can be boring for the girls, great for them getting some downtime for a couple of days, but hard for any longer, so I arrange for friends to visit.

The girls are funny about vacation care. Complain about having to go, but generally have had a great time when I pick them up. I try where possible to pick the days with the better activities, like excursions. It does cost more, but they get to have a great day. They are often zoo, wildlife park, adventures trips so well worth the $$.
It is provided by the council, and booking open 3 weeks in advance, so as long as I am organised in that first week, I get the days I need.