I saw it five times in the theater, including the first December 19, 1997 showing at Hollywood's Manns (Grauman's) Chinese Theater, and a "Tribute to James Cameron" showing in February 1999.
I also saw it once on TV (November 2000) and a couple of times on video, both regular and widescreen versions on VHS. I will have to make it a point to watch the Special Edition this weekend.
Another unique venue that probably few others had: July 1998: after being on a THS-sponsored tour of Ireland, Wales, and Southern England (followed by a personal side trip to Paris), I watched Cameron's TITANIC on the British Airways (BA) flight from London Heathrow Airport to Los Angeles International (LAX). BA showed the film in two segments, instead of two separate films for the flight.
The woman seating next to me commented "I know you'll be watching the film" (we had discussed our travel itineraries, mine completed and hers about to begin). The two of us, along with the woman's mom, enjoyed a mock "Hello Don Lynch!!" at the Sunday deck scene.
That was also the one time I remember people on a plane being truly interested in the in-flight movie: at one point a man about four rows ahead of me got up then started talking to his seatmate. The man received a rebuke ("Will you please sit down!!") as he was imposing on, if not blocking, the movie screen; he quickly sat back down after he realized he was the unwanted focus of attention.
Turned out that in July 1998 many of the airlines were showing TITANIC on the long-haul flights. My parents told me it was also shown on their Frankfurt to Dallas American Airlines flight (they were flying home from a wedding in Germany).
Did anyone else see the film while on an airline flight?