I saw the Lord of the Rings films 3 times each (I think I may have went to see Return of the King 4 times) and the first two Hobbit movies 2 or 3 times each as well. I can't remember if I went to see any other films 3 or more times (though I may have done), but having seen a film twice at the cinema is definitely not that unusual for me. If it was really good or if I am a big fan of the franchise then sometimes I'd want to see it again quickly rather than wait for it to come out on DVD / Blu-ray. And even for movies that are just OK, very often I might see a film twice just out of circumstance, e.g. going to see it with friends and then going to see it again with my family when they go, or vice versa.
On the subject of the box office record, here are the top few films for both Worldwide box office and Domestic (i.e. USA) box office, with their total gross (in millions) as well as how they compare to Avatar's gross in that market (so Avatar's gross is 100%, a film that makes half as much is 50%, etc.):
Worldwide
1. Avatar - $2,788m (100%)
2. Titanic - $2,186.8m (78.4%)
3. Jurassic World - $1,665.8 (59.7%)
4. Marvel's The Avengers - $1,519.6 (54.5%)
5. Furious 7 - $1,514.8 (54.3%)
6. Avengers: Age Of Ultron - $1,402.8 (50.3%)
7. Harry Potter and the Deathly Hallows Part 2 - $1,341.5 (48.1%)
Domestic
1. Avatar - $760.5m (100%)
2. Titanic - $658.7m (86.6%)
3. Jurassic World - $651.8m (85.7%)
4. Marvel's The Avengers - $623.4m (82.0%)
5. The Dark Knight - $524.9m (69.2%)
6. Star Wars: Episode I - The Phantom Menace - $474.5m (62.4%)
7. Star Wars (A New Hope) - $461.0m (60.1%)
The thing worth noting here imo is how much further ahead the James Cameron duo is in the worldwide box office compared to the USA. For example Jurassic World's domestic gross is over 85% of Avatar's domestic gross, and it almost overtook Titanic. Yet on the worldwide level, Jurassic World (which by no means did badly with global audiences) didn't even reach 60% of Avatar's total. So while other big films are regularly grossing quite close to Avatar in the USA, none are coming close worldwide.
Also worth mentioning that there are different films on those lists - a film being near the top of the overall chart in the USA doesn't necessarily mean it will make the same position worldwide. And notice a couple of films that appear on the US list but not worldwide? Star Wars. You have to go down to #20 on the overall worldwide box office chart to find Episode I, and the original Star Wars doesn't even crack the top 50, despite them being #6 and #7 on the domestic chart.
So seeing those numbers (Avatar not being quite as far ahead of the chasing pack in the domestic box office, and the Star Wars franchise historically doing much better in the US than globally), am I really the only person here that thinks Star Wars 7 might take #1 all time in the domestic box office but not make #1 all time worldwide? I mean, it could be that the market has changed enough and this is the Star Wars film the global box office is ready to really embrace making it #1 in both, or Star Wars could "fail" to pass Avatar's domestic haul and not be #1 in either, but to me it seems as though there is a pretty gaping space in the middle for Star Wars to become #1 domestic but #3 or #2 worldwide, and that might just be the sweet spot for it.