Playing melodies by ear is a great way to practice and use major scales.

Patriotic SongsStarts on the scale degree
America (My Country Tis of Thee)1st (do)
Battle Hymn of the Republic5th (sol)
Star Spangled Banner5th (sol)
America the Beautiful5th (sol)
Dixie5th (sol)

Christmas SongsStarts on this scale degree
Joy to the World8th (do)
The First Noel3rd (mi)
Silent Night5th (sol)
Away in a Manger5th (sol)
We Three Kings5th (sol) -- minor scale
Infant Holy, Infant Lowly5th (sol)
Frosty the Snowman5th (sol)
Rudolph the Red-Nosed Reindeer5th (sol)
The Little Drummer Boy1st (do)
Hark the Herald Angels Sing5th (sol)
Deck the Halls5th (sol)

HymnsStarts on this scale degree
Tis So Sweet to Trust in Jesus3rd (mi)
All Creatures of Our God and King1st (do)
Come Thou Fount3rd (mi)
A Mighty Fortress is Our God1st (do)
Amazing Grace5th (sol)
Great is thy Faithfulness3rd (mi)
How Great Thou Art5th (sol)
Be Thou My Vision1st (do)
How Deep the Father's Love for Us1st (do)