My father regularly travels around the US and outside for business (he teaches seminars). He probably travels at least once a month within the country, and at least 3 times a year outside the country.

His passport has his full name, first middle last. He hates his first name, and uses only his initials to friends and family, DP [lastname]. Most of his frequent flier cards use DP, as does his ticketing. He has never encountered a problem. Whenever someone asks, he pulls out the three additional forms of ID he carries on him, and explains that he dislikes his first name and refused to use it. No worries, no hassles.

The fact that it is DP on his driver's license helps, most likely :P