Add9 and sus2 chords always sound nice :) The G will introduce a new sound to your song, as it's not part of the C#m key.

My newest tutorials:
Pentatonic Speedster
Funk Lick Library A2
Bat Country
Funk Lick Library A1
Tapping: Level 4
Tapping: Level 3
Alternate Picking: Level 2
Find all of my lessons here:
Complete Lesson Catalog
Pentatonic Speedster
Funk Lick Library A2
Bat Country
Funk Lick Library A1
Tapping: Level 4
Tapping: Level 3
Alternate Picking: Level 2
Find all of my lessons here:
Complete Lesson Catalog