What you need to know about using Costco to book your next vacation

Did you know that in addition to being able to bulk shop for peanut butter and toilet paper, your Costco membership also gives you access to a travel agency?

That’s right. Costco has an extensive travel program for members, with a heavy focus on packaged hotels, cruises, and rental cars. And before you say those types of vacations aren’t for you, consider that they can offer a really good value.

“It’s a big world out there, and if travelers can’t find the time to plan their perfect trip, package tours or vacations are a great way to make sure you hit all the highlights,” Alex Howard, chief editor of the Lonely Planet homepage and told CNBC Make It.

In fact, if you’re on a budget, Costco offers a rotating selection of “$499 or less” deals, where you can get an entire vacation for under $500 per person. Right now, Costco is offering a four-night cruise to the western Caribbean aboard the Norwegian Pearl in an ocean-view room for $449 per person.

But before hitting the “book now” button, here are eight things you need to know about planning your next trip through Costco Travel.

You can browse Costco’s travel deals, but to book through the website or call center, you’ll need to provide your Costco membership number. According to the retailer’s website, a basic membership to the wholesale club will run you around $60 a year.

If you plan to shop and travel with Costco often, then you might want to consider the executive membership, $120 a year. Executive members get 2% cash back on all Costco travel purchases. That’s a benefit worth up to $1,000 a year.

Executive members also get access to exclusive travel perks and offers. For example, if you book a nine-night Moselle and Rhine cruise with prices starting at $3,999 per person, executive members will receive an onboard credit of $50 per person.

Pauline Frommer, Frommer’s tour guide company, tells CNBC Make It. When Frommer’s was recently researching Cancun, Mexico, and the Maya Riviera, the team found that people saved an average of 30-40% by booking a package for that destination.

The package is best suited if you’re traveling to resorts, theme parks, or a tourist-friendly capital city, where there are plenty of hotels, says Frommer. But if you’re heading to somewhere like Cleveland, you probably won’t save much with a package because there’s less competition among local hotels.

When it comes to getting the best rates on holiday packages, size matters, says Frommer. “Discounts are based on middleman influence,” she says. Negotiated rates usually depend on the number of rooms or seats by the airline or cabin that the travel operator can guarantee to move if well discounted.

So in this respect, Costco may be at a disadvantage, as the wholesale club may not be the size of companies like Expedia. “I don’t see any evidence that packages are better at Costco,” says Frommer.

Costco only works with certain airlines, travel agencies, hotel chains, and car rental companies. So if you’re looking to rent a car with Hertz, for example, you might be out of luck. Or if you want to book flights with a low-cost airline like Norwegian Air Shuttle, you’ll need to do that separately.

If you collect loyalty points for airlines and hotels, you may not receive them when booking through Costco Travel. Costco’s website notes that you can only enter loyalty counts for Avis, Budget, and Enterprise.

The most valuable part of Costco’s all-inclusive vacation deals, says Frommer, may be the extra freebies it offers.

These perks can include complimentary breakfast, activities, and resort or boat credits. An extra like “the kids eat for free” can be worth several hundred dollars for a family, depending on the length of the trip and destination, says Frommer.

For car rentals, Costco really shines. Wholesale Club offers an extra free driver at US Alamo, Avis, Budget and Enterprise locations for any car rental booked through Costco. Also, if you book through Low Rate Finder, you can cancel without paying any penalty fees.

Nowadays, it’s hard to get an affordable vacation at theme parks. “The problem is that Disney, and to a lesser extent Universal, has made it harder and harder to keep up with respite,” says Frommer.

Frommer recommends that if you’re booking an all-inclusive vacation to an amusement park, read the itinerary carefully. You can sign up for a ride that includes amusement park admission every day you’re in Orlando, even on the first day when your flight doesn’t land until 4 p.m.

“You really have to look very carefully at what you want to see and do, so you make sure you don’t have to pay for things you don’t use,” she says. And if you want to visit both Disney and Universal in Orlando, it may be more cost-effective to book each separately, as most vacation packages don’t include admission to both parks.

You should shop around to make sure you’re getting the best price. Frommer recommends checking flight costs for your travel dates and destinations on Momondo and Skyscanner, where Frommer’s usually offers the best prices. For hotels, she recommends checking prices on Booking.com. As for cruises, usually CruiseCompete is the biggest online travel agency in the game.

If a Costco plan costs less than the total cost of booking all of the trip components separately — or fairly evenly, but offers additional amenities — then you can feel good about booking in advance.