DH & me have been married for over 40 years.
He had his own business & worked very long hours. We had 3 DCs within the first 5 years of marriage & I reduced my hours to P/T after DS1 was born. After all the children were in secondary school I increased my hours to F/T as they were all at the same school & able to get themselves to/from school & I was around to take/collect from after school activities.
DH & me have always had a joint account for household expenses (when we had DCs at home this included the cost of their clothes, activities, pocket money etc) which we review about 4 times a year as the cost of living increases. We've always had our own personal current & savings accounts.
When we had DCs at home we would split the cost for our holidays 50/50 between us both & each pay 50% of DC's costs - though, as I remember DH used to pay all of DC's & pay for meals, bar bill etc when I was working P/T as he was earning vastly more than me.
Both DSs went into the Royal Navy on leaving school so, as they were travelling the world from the age of 16/17, never came on holiday with us again preferring to spend their leave enjoying the comforts of home.
DD went to University so came on holiday with us until after she'd graduated. DH & me would split the cost of her holiday 50/50, but she was expected to find her own spending money (she worked in DH's business during holidays & weekends when she was home so that wasn't a problem for her).
DH & me have always managed to find the time for the odd short break (talking a couple of nights in DH's business 'off season' eg: winter) when PIL or my parents would look after the DCs. We would 'treat' each other to these breaks. By which I mean, if I'd arranged the break I would pay from my own money (though when I worked P/T DH would pay for the meals out, petrol, the bar bill etc), if DH had arranged it, he would pay.
These days we still pay 50/50 for main holidays & still treat each other to mini breaks. For example: we're going away for 3 nights at the end of March, I'm paying, again for 2 nights in July (obviously July will be more expensive than March) DH is paying. We're going away for a week in May - 50/50, 2 weeks in November 50/50.
It works well as DH will say 'no, you paid for the break in x place, it's my turn to pay' & I will do the same.