We fell in love with 3D and I still have all the discs because as you say, they're packaged with standard copies as well.
We had to buy passive 3D because the active method would give my wife migraine headaches.
Just checking my online film list, I didn't realise I had 38 3D films in total. I think Tron:Legacy was one of my favourites. Also, I know it's hated (I disagree) but Ghostbusters (2016) renders some of the VFX shots into the black borders. This gives the film a 3D feel at times but when I watched it in "proper 3D" the effect works really well with the proton streams coming out of the TV.
Alternatively, something like Dredd 3D was quite disappointing. The slo-mo sequences looked great in 3D but to be honest, when watching the rest of the film, I forgot it was even in 3D!
In the end, I purposely bought 3D copies of The Hobbit a few years ago because they were cheaper (at CEX) than the standard copies despite having the same content.
Sadly though, our 3D TV died many years ago and because everyone was bored of the format, no new 3D TVs were being sold otherwise we'd happily get another one.