Well, what's the most important here? Reading for life, right? People who read for pleasure don't always read classics---compare the princess stories to a good sci-fi or "trashy" dramatic novel you might enjoy. The point is that reading is fun as well as a learning activity.
But I understand that you want your girl to enjoy these stories. This is just what we do, which may or may not apply to you....
We read every day with my (5yo) dd, and pretty much have her whole life. When she was younger, I would keep a stack of visually interesting board books or books that have great rhythm (Dr. Seuss!) We would read in 5 or 10 minute spats---any book she was interested in, any time all day, taking "little kid" books with us everywhere. I'm sure lots of families do this.
Reading was a very fun, positive activity at that age, never a drag for her. You don't want her to associate reading with being a droning, boring, academic activity. LOVE of reading is the most important thing you can give her, Beatrix Potter will come later; I promise!
That said, we have cultivated a habit of enjoying a bit of "heavy reading" (Through the Looking Glass, Peter Pan, etc.) before bedtime. When she was smaller, we would read several short "fluffy" books and then finish off with longer one, or one with less pictures, or something "literary" (Shel Silverstein
esp. for weaning kids off the mega bright commercial stuff).
At that age, I admit, part of my motivation was to read for a really long time to wear her out before bed, LOL, but the effect has been that she now is able to enjoy the longer books (Peter Rabbit, non-illustrated folk tales and such) that at 3 or 4 she just didn't care to hear.
Now that she's older, we still read our old board and little golden books, but our big reading time is the bed time story, which is almost always longer (the story can last over several days---younger kids don't enjoy this til later?) and is not limited to "child" vocabulary. She doesn't interrupt to ask a ton of questions or fidget. We've settled in that this is a quiet time to relax and listen to mom (or dad) read a nice long story. This has never been forced
, tho. We tried Peter Rabbit before, and she wasn't interested. We'd read a few pages, and put it back on the shelf. Recently, it's come back up and seems to hold her attention.
Don't despair, just put the "big books" on the shelf for a few days and just get down and really have fun reading with your kid. Slip a longer story in from time to time to see if she's more tolerant.
I will say that the badly written stuff has slowly been weeded out. I don't give away the ones she's attached to (Mickey's Christmas Carol
I know; Dickens, right?). We do have lil golden books of Pinochio and other "commercial" stuff; but I pick and choose what works for us.
ie--We may read Grimm's Fairy Tales for read-aloud time, but I may give her the My Little Pony books for her b-day. Why? Because I think they have high literary quality? Ha! No, they make me pretty gaggy, but
my budding reader would nearly explode with joy if they were hers, and she'd enjoy the act of reading. <shrug>
My Lil Ponies are her style; not mine. I'm an old fashioned fairy tale kinda girl. And she's okay with that. She's a sparkly princess kinda girl. And I'm okay with that, too. I'm not going to plaster her room with it, but if a little pony story makes her happy, who am I to deny that, eh?
I've heard some good advice that's hard to do: hold a little back. If it's a book that might become dry after a chapter, only read a page. This drives kids crazy! They want more! You must not give in, lol! If they are still a little curious or hungry to find out--the book mom only gives us a taste of will become anticipated.