One thing that we found helpful in finding books that were generally good quality (as opposed to looking for a particular lexile level or something) was to run down the Caldecott medalist lists (and later, the Newbery winner and honor books).
Since we were checking things out at the library, I didn't worry too much if something were a real hit with DD or not. If not, back it went, and if so, well, then if she LOVED it so much that I had to renew it several times... that was a book that we put on our wishlist.
Some of the wonderful picture books that we bought because we loved them so much:
The Rainbow Goblins
Doctor Dog (this one may appeal to the same crowd that will later fall head over heels for Captain Underpants, by the way, but we LOVE this book and still recite it sing-song occasionally.)
I also bought some beautifully illustrated books of poetry for children, a complete set of Shel Silverstein, and several nicely illustrated editions of Alice in Wonderland, the Wizard of Oz, The Velveteen Rabbit, and fairy tale anthologies. Kate diCamillo is probably just a touch old as of yet-- but Edward Tulane is a lovely story which is probably great even now as a read-aloud, and the illustrations are wonderful.
Generally, as you go OLDER (in terms of publication dates), you get higher lexiles with lower "interest" scores. That is, the younger content comes with higher level literacy. It also, unfortunately, comes with some interesting cultural baggage at times, so do be cautious about that and read carefully.