I posted earlier, but had several thoughts about this that I did not put in my first post.
When I plan I try to include everything... to see what the actual cost is really going to look like. So of course I look at the major items, Airfare or driving to and from. Resort/Hotel/Homeaway, Food. But that's just really the body of the budget then, I start drilling down, adding all the vital organs, and such...
Air Fare - Flight cost and with that goes, are we parking at the airport, or Ubering/Lyft to and from the airport. Food in the airport both ways, a couple of bottles of water or soda for the plane trip, in flight cost wifi, or food or drink cost, baggage fees.
Driving - cost of oil change, tire rotation before we leave, Gas to and from, stopping for meals, and when you stop for gas snacks and drinks. Emergency money for car repairs.
Resort/ Hotel / Homeaway - Room cost per night... if we are driving cost of parking, wifi, resort or hotel fees, if rollaway or crib is needed.
Then the activities, tickets to theme parks, museums, shows/concerts/ zoo, zip-lining, horseback riding, snorkeling, spa treatment/couple massage, private tours, dinner cruises...the list goes on and on.
Car rental at destination if we are going that route, gas, mileage.. and we always get the insurance.
Transportation at destination - private car service, uber/lyft, hop on hop off buses, trains/metro/subway.
Food, Dinning out, cooking at Homeaway, snacks, treats, adult beverages, drinks - coke, water, diet coke, Gatorade for in room, as well as tipping the servers. I look at what we spend out for dinner at home since we live in a tourist meca, our cost of dinning out is high, then look at the area we are traveling to, I know that in NYC, Vegas, Paris the meals are going to be more expensive, and plan accordingly.
There is alot of tipping when you travel, servers, baggage handlers, bartenders, bell boys, uber/lyft/taxi drivers, even if the tip is included and we get above and beyond service we do tip something extra.
The before trip spending, clothing, shoes, beauty/personal care items, a heavy coat that will be need or swimsuit/coverups, sunglasses, sunscreen, thinking about that, I do start shopping months in advance so I am not spending a chunk of money right before we leave. Getting you hair, nails done before the trip.
When we take a cruise, hotel the night before with dinner, as well as brunch when we return, parking at the cruise port, cost of excursion the ones that I know that we will want to do, soft drink packages, adult beverages, money for gambling, spa treatments, and any out of pocket meals that are not included such as a specialty restaurants, or on board activity such as kids and teens clubs.
Currency Conversion - what's our dollar worth, where we are going.
For me taking the time to drill into where you are going, really thinking of all the stuff you will need, want do you want to do, and see. Any experiences that you must have. For me I like to know a more realistic number so that I don't have a ton of extra unexpected CC bills after we get back. By really looking and planning, you learn things, read tips, and can find deals, and information. There is so much out there, by planning at least for me, it helps me keep the budget in line, and helps us do the things we want to do.