Personally, I'll take as much as I can get, within reason and within what is allowed by policies. I will book the airline and time that is most convenient to me, and stay where it is most convenient to me. And yes, piles and moints come into play quite frequently, although lower-cost alternatives exist for virtually all my travel.
The decision of what is convenient is made by me, travel books it, and reimbursements gives me my money back. Neither travel nor reimbursements have any clue why I do what I do, and I like it that way.
To give and example, I am about to start a RTW trip to visit a client in the US, in oneworld First, which cost me about $6,300. The client budget allows for $6,000 for airfare for this trip. What do I do? I bill $6,000 to the client, and pay the rest myself out of pocket. I could have taken a RTW in business class, for less than $5,000. The client gains, but if it is in the budget, might as well take advantage.
It is not my policy to provide charity to my clients or increase the bonus pool for everybody at my firm by self-sacrifice.