Have turned domestically at:
LAX, SMF, SEA, PHX and transits at DTW, MCI, MEM, TPA, FLL, MSY and others I will probably remember after hitting "Submit."
International runs (with between 1 and 24 hours time at destination) include: YVR, YYC, YEG, YUL, YYZ, LHR, BRU, and SIN.
Have ONLY had one minor problem at LAX and that happened in October 2001 (tensions were still running high). It required an "interview" with the captain before boarding and was set off because we were turning with the same crew (which we've done many times before and since). All ended fine.
Both my partner and I are white. He's an American citizen, I am not.
Many years ago, coming into the US from Canada (pre-clearing at YUL), I learned a very important lesson. Be direct in telling the immigration officer what you know he or she wants to hear. If you happen to be "stretching the truth," make sure your story is tight and well-rehearsed.
Most often, it's best to simply tell the truth. Your confidence is often the deciding factor between a hassle and a stamp n' smile.