The fun side of you says, “Vacation!’’ but the practical side says, “That costs money!’’ Perhaps this will be the tiebreaker: After several years of prices going up, airfares will likely be lower this year, on average. “This decrease in fares is due to the low price of oil we saw in 2015, and an increase in airline capacity,’’ says Tom Spagnola of CheapOair.com. The major airlines’ capacity is expected to grow by 3 to 5 percent in 2016, and low-cost carriers are seeing double-digit capacity growth. New low-cost carriers, coupled with major airlines adding flights to popular routes, are keeping prices down.

A report issued in December by Expedia and Airlines Reporting Corporation showed that airfares were 8 percent lower in October 2015 than they were a year earlier, with a 5 percent decline for flights within North America. Fares for travel within Europe declined 16 percent, making these routes among the best bargains in 2016. Here’s how to nab the best possible deals, and a look at some value-packed destinations.

When to book that flight

Expedia data shows that travelers care more about price than anything else when they’re booking travel. But finding the best airfare is time-consuming. Should you buy now, and risk that fares come down, or wait, and hope that they do? According to the Expedia/ARC report, the best time to buy economy tickets for travel within North America is about 57 days in advance. For trips to the Caribbean from North America, the optimal booking time is 77 days, while trips to Europe are lowest, on average, 176 days before departure. The sweet spot to get the cheapest fares to Asia is 160 days in advance; for the Middle East and Africa, it’s 144 days. If you’re heading to South America, your best time to book is 90 days before takeoff. Research shows that this strategy yields a savings of 10 percent over the average fare.

What day of the week should you book? That’s a tough one because airlines are constantly adjusting prices. Generally, the weekend is a good time to find deals, because that’s when leisure travelers purchase tickets. Business travelers, who pay higher fares, book their reservations during the week. Stay away from Fridays, when air tickets are typically priciest — 13 percent higher than those bought on Sunday, according to the Expedia/ARC report.

Fare sales? Good luck finding a seat on a plane that’s going where you want to go, when you want to go, that doesn’t have, say, a 23-hour layover in Newark. Forget about last-minute discounts, too. You’ll pay dearly for an impromptu getaway.

But the Expedia/ARC study revealed a way that travelers can save money: By booking air, hotel, and rental car as a package. Package deals can deliver discounts across the board — an average savings of $226 based on actual bookings in 2015. This is especially true in resort destinations like Mexico, Hawaii, and the Caribbean, where savings can range from $800 to $1,100.

Top picks for affordable travel in 2016

We asked Spagnola for his top picks for affordable travel this year. His choices, based on average round-trip airfare, are San Juan; Cancun, Mexico; Chicago; Fort Lauderdale, Fla.; Las Vegas; Paris; and Milan. Spagnola also likes Central and Latin America for value-minded travelers. To find deals from Boston, play around with the Explore tool on Kayak.com. Go to kayak.com/explore/Boston to see a map with prices; click on the price to see the deal.

Other destinations that look promising for value-minded travelers in 2016? Sydney is typically a pricey destination for Americans, but may be more affordable this year, as some economists predict that the Australian dollar will be trading at 50 cents to the US dollar by the end of 2016. Factor in increased competition among air carriers, and travelers are likely to see significant price cuts to Australia.

Savvy travelers (and budget-travel bloggers) sing the praises of Lisbon for good reason. The prime pleasures of this city of seven hills are inexpensive ones, like sampling pastels de nata (custard tarts) at a corner bakery, and wandering up winding hills to sites like Sao Jorge Castle. The famously cheap Tram 28 hits all the highlights. On the first Sunday of the month, many sites and museums are free. You can even score a cool, centrally located hotel without breaking the bank, such as the ultra-stylish, 55-room Internacional Design, home to Bastardo, one of the city’s best restaurants. idesignhotel.com; from $109.

“As pretty as Paris, without the price tag,’’ a friend recently raved about Prague. Affordable cultural sites, hotels, and meals make “the city of 100 spires’’ a great choice for bargain-hunters — especially now that Norwegian Air Shuttle (norwegian.com) is an option for travelers flying out of Boston. See attractions like Prague Castle, the astronomical clock, colorful baroque buildings, and Gothic churches, and sample some of the world’s best beer — but be sure to use the metro, not (tourist-gouging) taxis. www.­prague.eu.

They’re conveniently close by, the weather is enticing, and you can luck into some great travel deals (especially in April and May), so why not make this the year to check out the US Virgin Islands? These islands offer lovely beaches and average winter temps of 77 degrees. Check out www.visitusvi.com for special promotions.

According to trivago.com, hotel rates are trending downward in the Eternal City. More reasons to visit, or revisit, Rome (www.turismoroma.it) this year:The restoration of the Colosseum is now complete, and the Trevi Fountain has had a facelift. If you’re looking for a bargain place to stay in the heart of the city, and don’t mind a curfew, consider a monastery. www.monasterystays.com

Diane Bair and Pamela Wright can be reached at bairwright@gmail.com.