Heh, seeing Star Wars for the first time around the tender age of seven, I totally thought it should be Luke and Leia. I didn't like Han at all; I found him to be abrasive and awful while Luke was good and true, and his interference was something that had to be overcome.
When I saw Empire a few months later, I was horrified by the Han/Leia storyline. I was convinced that he had somehow 'tricked' her into loving him, and that this was wrong and bad. That, combined with Vader being Luke's father and the way the good guys are so utterly defeated, freaked me out and made me really dislike Empire, and it was a long time before I dared to watch it again.
I didn't see Jedi until I was nine, since I had seen the others on my aunt's Beta player which was on the verge of breaking down. Actually, I read the novelisation first since my school library had it, then sought out the movie . . . anyway, the 'revelation' of Leia as Luke's sister certainly took me by surprise, but it worked in its purpose, for it satisfied me that they weren't actually meant to be as a couple. Actually I think it worked better by reading it first, since the book had the scene's extra dialogue and backstory, explaining the circumstances of their birth and separation and so forth. (This information, of course, is partially contradicted by the prequels, to my great annoyance.)
After that I was able to go back and watch all three movies and enjoy them all while viewing them as a cohesive story--even if it did take me a while to develop an appreciation for Empire on its own terms, or Han as a character. I didn't like sarcastic or irreverent people at all back then, which was part of the difficulty I had with the idea of Han and Leia. Today, however, I myself am often quite sarcastic and irreverent, so it no longer poses any problem. lol
I know now that Lucas basically made up the idea of her being the sister and the 'other' at the last minute, but it doesn't really bother me. For one thing, the RotJ book strongly implies that she unconsciously used the Force to help her strangle Jabba, since nobody would have been physically strong enough to do such a thing otherwise; for another, this works in considering how she was able to withstand Vader's interrogation in the original film. More importantly to the topic, being more understanding of such things than as a kid, I see how Han and Leia was always a much more interesting and valid choice in writing the romance aspect, so it completely works.
Still, I'll always remember those early days when I thought it should have gone the other way. ;)