United Airlines customers will have to spend more to reach frequent flyer status next year, the latest move by the carrier to increase profits and give an exclusive feel to the increasingly crowded top ranks of airline loyalty programs. The thresholds to earn elite status on the airline's MileagePlus program are going up about 25% and include either spending on a co-branded card or a combination of spending and flying. The status earning requirements and accompanying perks earned next year will be valid in ...