Yeah, I saw one at JFK in 1992, at CDG in 1993, at LHR in 1994 - all on the ground at gates. The most spectacular, though, was when I watched an Air France Concorde take off from Brown Field, San Diego in 1988.
I found out when it would be leaving and drove down there from Coronado, which is where I was living at the time. I parked my car at the end of the runway and watched the plane taxy down, turn, and rev up for take-off. I couldn't actually see the aircraft at the opposite end of the runway, but I heard a roar and saw a big cloud of exhaust, then a white shape that grew in size until I could make out the on-rushing aircraft. I watched it lift off, rotate and then it shrieked almost directly over my head. I took pictures the entire time, capturing it from the moment it became visible until it had passed over, afterburners flaming. I went nearly deaf from the noise, and shouted, "VIVE LA FRANCE!!!" at the top of my lungs! What a rush!!!