Savvy business travelers know to collect miles and points, which can later be cashed out for discounted airfare. Recently, there's been an increase in the availability of these "award" seats.

Research from Switchfly, a startup that provides technology to airline rewards programs and credit card companies, found that the number of free seats open for booking on major airlines has increased for the third year in a row. The company's 2016 Reward Seat Availability Survey made 7,000 queries in March of this year at each of 25 air carriers, for trips between June and October. Two or more seats were available at the lowest mileage level for 77 percent of queries, up from 74 percent last year and 72 percent in 2014.

Unsurprisingly, because rewards (like vacations) are seasonal, availability was generally higher in the fall than it was in the summer. "Overall, I think the consumer is being better served than the year before," noted Jay Sorensen, the president of IdeaWorks -- the consulting firm that conducted the study -- in an interview with the Wall Street Journal.

Still, travelers find it increasingly tricky to cash out miles during peak season, and airlines may force them into choosing more expensive redemption deals; nearly one in four queries came up with zero "saver-level" seats available on each airline's busiest route, the survey found.

Southwest Airlines was named as having the best rewards program. It comes out on top for the fifth year in a row. Southwest and JetBlue, which had seat availability on 93 percent of requests, offer the strongest programs because they let users earn points based on the price of a ticket, rather than the distance traveled, and they can later choose to cash in either points or miles.

American Airlines was ranked among the worst air carriers for loyalty programs, second only to Avianca and LAN. It had seats available on just over half (56 percent) of requests, down from 67 percent the year before.

Other air carriers, which fare moderately well in terms of availability, are getting more creative: Delta Airlines, for instance, will let members buy drinks with their miles at airport bars. Beers and spirits range from 600 to 800 miles. The company has been making a concerted effort to improve its program in recent months, and in the first quarter of 2016, it issued a record 2.2 million award tickets, as the average price was down 10 percent.

Of course, not all airlines provide the same awards at the same cost, and it's helpful to do some research ahead of time. A handful of startups, such as Farecast, FareCompare.com, and FlySpy help you scour the best airfare deals (and ensure you don't cash out your hard-earned miles for a sub-par price.)

One expert tip: Remember that you can book awards with partner airlines. So say you're looking to fly from Los Angeles to New York City, and there aren't any award seats available through United; a seat on the same flight could become available when you redeem those miles through Air Canada, a United Airlines partner carrier.