Wet - Nicole Scherzinger ( I thought it was a smash hit in the uk )
Your Body - Xtina
Marry The Night - Lady Gaga
Who Owns My Heart - Miley Cyrus
Boss - Fifth Harmony
A Thousand Years fits this as well. Played on radio, covered on many talent shows, sung at weddings. Everyone pretty much knows this song but it only peaked at #31 on the Hot 100.
To be fair, you'd think "Jar Of Hearts" would have been bigger too.