Would the Stephenie Meyer books - 'Eclipse' and The Short Second Life of Bree Tanner be suitable for a 14 year old?
Yes, though I haven't read the second book you mentioned. You may want to check that she's read the first two of the Twilight series though, because Eclipse is the third. The fourth also has a little bit of vaguely described sex, but most 14 year old girls should be able to handle it.
On to the other discussion. I disagree with the types of things Twilight is said to promote. I don't see the Edward-Bella thing as an almost-abusive relationship. At no point is Edward what I would consider to be abusive. The "I hang around your room watching you sleep" is a tad creepy, but that's how I see it. Teenage girls could choose to see it as sweet, protective, or even just an odd personal quirk of Edward's. They're not necessarily going to carry around the ideal that being watched at night is desirable. If they do, the real world will soon knock it out of them - most 14 year old boys aren't equipped to sneak into people's houses at night and watch their daughters.
On the "No sex before marriage" thing. Is that really a bad thing? Sure, it's a little bit outdated, but at least she's not encouraging teenage girls to sleep around. The insistance on no sex before marriage is part of what completes Edward's character. He's from the 1900s, he thought that way. It completes his image as something frozen in time (unfortunately, nothing else in the story lends itself to this)
And I'm pretty sure that teenage girls aren't going to pick up that Bella is doing anything the can for Edward - there is no servile attitude. Romantically, she loves him so much that she
wants to. Edward doesn't take advantage of this. He doesn't plot around it. I see no problem.
As with any novel, you can twist events, character traits, and pieces of conversation to make them seem more sinister.
Harry Potter is a book about three young people who eventually learn to kill things! It's horrible! They fight with people around them, and there's so much bullying in the books. I don't want my child to read this incase they think that is normal.
Etc.
Twilight wasn't intended to be sinister. It wasn't intended to impress moral values on young girls. While it may have had that effect, I wouldn't blame it on Stephanie Meyer. I wouldn't have marked it as aimed at anyone under 15, but the culture has seized upon it, and now 10 year old girls are reading it. That's hardly her fault.
I don't conform to the "I used to like Twilight, but since it's become so cool to hate, I hate it".