The main theme connecting the two books I think, is that of obsession. Also, I think that this obsession theme goes further than jsut Wuthering Heights and Twilight. It seems to be there in every vampire novel/movie/whathaveyou. Humans have a certain obsession with vampires and vice versa.
Heathcliff has an obsession with Catherine that transcends her death and goes on to punish everyone connected to her...Hareton, Linton, and Edgar.
In Twilight, Edward also shows this obsession although it is very different from Heathcliff's obsession. Edward's main concern in life is keeping Bella safe. He does whatever he can to do this, sometimes sacrificing his family, and almost always sacrificing himself.
In both of the books, the obsession seems to win out over love. In Twlight, Edward knows that he is no good for Bella but his obsession/love for her wins out over this notion.
Same for Wuthering Heights, one would think that because Heathcliff loves Catherine so much he would want to do right by her daughter, young Catherine. But no...Heathcliff can see nothing besides his deep need to get revenge on Catherine in any way, shape, or form possible.
In Eclipse, Stephenie Meyer uses a number of quotes to compare the relationship Bella has with both Jacob and Edward to the relationships that Catherine has with both Edgar and Heathcliff. Bella and Catherine both have two great loves.