I spent $910 for a roundtrip United flight from Newark to London - and it was worth every dollar when I got my first upgrade to Polaris. Here's what the business class flight was like.

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• I've been a member of United's Mileage Plus program for 31 years and have flown 479,533 miles with them.
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• That puts me just shy of halfway to my goal of earning lifetime gold with United by flying one million miles.
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• In August, I flew from London Heathrow to Newark, New Jersey.
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• This was the first time I had ever been upgraded to their Polaris Business Class.
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• The experience was so good that I did not want to leave the plane. Having your own personal area and being able to lay flat made this the best flight I have ever been on.
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As United recently reminded me, I've been a member of its Mileage Plus program for 31 years.

Mileage Plus is United's loyalty program that allows you to accumulate miles, all while earning different status levels each year. There are three status levels: Silver, Gold, Platinum or 1K. Members of the program must fly at least 25,000 Premium Qualifying Miles (PQM) and spend $3,000 each year to be a Premier Silver level member - and that's the lowest recognized premier level.

While these status levels only last for one year, United has a lesser-known million-miler program that will earn you a lifetime status once you earn 1 million miles.

Over the summer, I traveled to London Heathrow. I spent $910 on my roundtrip flight from Newark, NJ. As a planner, I try to book flights far in advance to get the best deal, but I delayed on booking this flight as I was traveling with my boyfriend and schedules were up in the air until a few weeks before. I spent about $200 more than I typically would have - but it worked out to my advantage because I was upgraded to Polaris Business Class for the flight back to Newark.

Here's what it was like to fly on United's Polaris Business Class - and why it was worth every extra dollar.