Be very careful with work-specific challenges - my husband completed a work gold challenge (Accenture) and even though he has it confirmed in writing from HH that he completed the challenge as required, they did not honour it as he was Gold HH at the point of qualifying (?) - i.e. it didn't just renew it for the relevant year he qualified. The challenge was set up in person over the phone, and the rep could see he was already gold HH, so you might think that would have been the time to mention it was pointless, but no. HH help desk were no use (did not understand and kept offering to set up another - possibly pointless - challenge). The HH FB rep said they would look into it and then promptly disappeared. He's now platinum with Marriott. He actually prefers Hilton but they are playing too hard to get.