Not enough information to adequately answer.
Are you having to pay for motel rooms, food, transportation, and attractions? How many nights?

Here are some general guidelines:
Avg motel room per night, all four people in same room, $85-$110 depending on season and where in Northern Ca (if you are talking Eureka, then $85, if you are talking San Francisco, then $150+).
Meals at a family restaurant, avg. $8-12 each. Fast food avg. $5-6 each. Take your own food in a cooler and eat out once a day to save money.
Attractions: Look up the costs of the specific attractions you plan to go to, then add it all up.
Also consider things like soft drinks, bottled water, souvenirs, unexpected expenses.
Then there is transportation, if you are driving, figure out how much gas your vehicle uses, then multiply by $3.50 per gallon needed on the trip (figure out how many miles you will be traveling, including to attractions and restaurants and shopping). Gas isn’t that much, but that also takes into account if you need oil or other minor items for your car.

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