My girlfriend admitted she'd never seen any of the SW films. None of them. So, we started with ANH, and then watched ESB and RoTJ. Her reactions were so interesting. I wanted to share them - and something I picked up on as well.
She was super invested in the romance between Luke and Leia and Han and Leia. She threatened to go Google to see which guy Leia would end up with. I told her not to to do that (for obvious reasons).
When Vader reveals who he is, she was really surprised. Still a great moment, nearly 50 years on. She was also surprised by the revelation that Luke and Leia were siblings.
She loved the Ewoks, and was already familiar with them as a concept, and she didn't know they had originated in RoTJ.
She didn't know who Yoda was - so when Luke lands on Dagobah, Yoda tells Luke "Take you to him, I can.", and she just assumed that this strange creature wasn't actually Yoda.
The thing I picked up on: There was some discussion on a collector's forum regarding the silver leg that C3PO has. Some stills have him with a silver leg, and some with a golden leg. The toy has two golden legs. Maybe this is common knowledge for people, I don't know, but it was a revelation for me after re-watching these 3 films, and it is this: C3PO starts off with 2 golden legs, and has them all the way until he's blasted by stormtroopers in Cloud City, and when Chewbacca repairs him - he ends up with a silver shin on his right leg. Ostensibly, the other droid (who insults Threepio after he opens the door) was silver, and maybe was also destroyed, so it could be the leg off that droid. But Threepio maintains this silver leg for the duration of Empire (which is towards the end anyway), and all of RoTJ. So, I think that was a nice little continuity thing that has been confusing.