7 times a flight upgrade might be worth your money

Upgrading your flight can be a good move if you want to accumulate miles, book a last-minute vacation, or have the flexibility to depart at an unusual time.
If you're looking to upgrade your flight without burning a hole through your wallet, here's how to know when it's worth the money.

I take dozens of international flights every year, which leads to the necessity of choosing upgrades for comfort. When I want more legroom to stretch out or ample seat space to get work done on my laptop, an upgrade comes in handy.

According to the Department of Transportation, the average domestic airfare was $347 in the fourth quarter of last year. The high cost of airplane tickets, coupled with additional baggage and seating fees, can keep many people from clicking the "upgrade" option.

However, there are some variables that can make upgrading a more economical choice.

1. Upgrading your seat may give you access to premium lounges.

When I was flying from Istanbul, Turkey, to Malé, Maldives, on Turkish Airlines, I decided to upgrade to business class.

Instead of having to pay a couple hundred dollars for a hotel room during my eight-hour layover, I used my business-class ticket to enter the airline's 20,000-square-foot lounge at the airport in Istanbul — it included a marble shower with towels and luxury soap, food served 24/7 at several buffets, and comfortable couches to rest until my next flight.

I felt that the upgrade to business class was worth it to be able to lie flat and sleep on my seven-hour flight. I ended up paying $999 at the gate, compared with $2,420 for a business-class round-trip ticket.

2. Some airlines offer last-minute upgrade deals.

Some airlines, such as Emirates and Malaysian Airlines, offer last-minute upgrades that are markedly cheaper at the gate than they would be if you booked the business-class ticket ahead of time. The downside is that you usually don't earn miles on the transaction and may not have access to the lounge.

On my Turkish Airlines flight from New York to Istanbul, I opted to upgrade the red-eye leg so I could sleep better but kept my economy seat for the daytime flight on the return trip.

That would not have been possible if I had booked the flight as a round trip outright, as my whole itinerary would have been designated business class rather than split between economy and business.

In the end, my total flight expense was less than if I had booked a round-trip business-class ticket up front.

3. If you're bringing kids on a long flight, consider an upgrade for better seating.

When traveling with kids on a long overnight flight, families may want to upgrade so everyone can sleep peacefully and arrive at the destination energized and ready to explore.

4. Airline rewards programs may offer free or discounted upgrades.

When you accumulate a certain number of miles with an airline's rewards program, you may end up paying only a small fee for an upgrade.

I accumulated 25,000 airline miles on Delta and used them to pay only $70 for an economy-plus seat for a one-way flight from New York to Los Angeles around last Christmas.

5. The difference between economy- and business-class tickets could be small when booking last minute.

If you book a trip last minute and are faced with expensive economy tickets, the jump to business class could be small — only a $100 to $200 difference round-trip, in my experience — which could make upgrading a good deal in return for comfort.

6. Taking flights during less popular times may mean an upgrade makes more sense.

When flying long-haul international, there are usually steep prices to get into business class or extremely restrictive limitations on upgrading with miles.

In my experience, if you have accumulated a healthy number of miles on airlines and have achieved a status like Platinum on United or Delta Diamond Medallion, taking flights at odd days and times may increase your upgrade probability.

7. Upgraded seats are more comfortable.

For business travelers, the ability to wake up from a flat bed rested and ready for work in another country can be worth the extra money for an upgrade.

For example, a traveler on a flight from Guangzhou, China, to Paris may be looking at $600 for the upgrade to lie in flat seats in business class. But it could be worth not having to deal with passengers getting up from the middle seat or neighbors trying to chat with you while you rest.