Hi Jay, its a hard time of year as it is school holidays & every man, women, child, family is trying to do the same thing.
If coastal all I can say is book early & put up with the crowds, it is what it is!
Fresh water lakes, rivers, streams are probably a less restrictive proposition which there are many options.
Lake Jindabyne/Eucumbene might be worth a go & you get to see some good country on the journey as well.
Yeh its a tough call at that time of year, that's why I take holidays in February when all the kids & adults have gone back to work