If you liked Simone Elkeles' books, you might like...

Lisa Schroder books
Pushing the Limits, by Katie McGarry
Stay with Me, by Paul Griffin
Along for the Ride, by Sarah Dessen
Romiette & Julio, by Sharon Draper
The Summer I Turned Pretty, by Jenny Han (this is a series)
Twenty Boy Summer, by Sarah Ockler
Waiting for You, by Suzanne Colasanti
Numbers, by Rachel Ward
You Against Me, by Jenny Downham
Two Way Street, by Lauren Barnholt
My Life Next Door, by Huntley Fitzpatrick

If you'd like some book summaries, check out these two sites:

http://www.iwanttoreadthat.com/2012/07/top-ten-books-for-people-who-like.html

http://www.librarypoint.org/bm_perfect_chemistry