I really liked when Elena first found out about Stefan. How that whole thing happened. She was all disgusted and he was so sure she was done with him... and then she decided she loved him anyway.

I didn't like how Elena died and all but when she got brought back it was just amazing. He was so hurt and he loved her so much... and then she came back! But I'm not exactly sure I'd like to see that happen in the show. I'd probably cry. but I really liked that part at the end of book 4.

Their first kiss, him opening up to her about Katherine and their blood exchange

When she finds out he is a Vampire, i love the way it was done. When she realizes, she didn't care what he was.. she loved him anyway

How Stefan went to Elena, after she had 'died' i loved how they wanted to be together.. it was so heartbreaking.. and she was trying to protect him from klause

When she came back from the dead, their moment there was

I really like how Stefan completely gives up with Katherine for Elena. He knows they are two different people, and he fell completely in love with Elena anyway.

Although, I think that might be in the series. From when Stefan says to Damon, "She's not Katherine."

He even said in the books, she may look like her.. but Elena was stronger than Katherine, had more independance, spirit than her.
She was everything Katherine wasn't.

And its nice to see Stefan making the different in the show too

Yeah Elena and Katherine are two totally different people, and I love Stefan for knowing that. At first you know that he talked to her because of the whole Katherine thing, but I love how stuff turned out in the books. And it looks like that's going to be coming up in the series too.