@Nightweaver20xx  
Celestia could cover Big Mac’s part without the use of poison joke. Luna is more of a Gloria Estefan conta-alto. Does this seem reasonable to you, or do you think Luna would be even deeper than that?

@PUBLIQclopAccountant  
Celestia has a larger frame and thus a larger neck and larger vocal cords. I think Celly could go into some deep bass territory, but Luna couldn’t.

The girl you left behind - James Horner

All Star - Smash Mouth

Which princess has the lower vocal range? I think it would be Luna.
 
@Background Pony #BE20  
“Walking on the Sun” by Smash Mouth

I’m sure she’d like nothing more than a break from it all, and have a chance to cut loose.  
I bet she’s singing:  
“Girls Mares Just Wanna Have Fun” Cyndi Lauper

“Singin’ In the Rain” — Gene Kelly

@Goddess Erosia  
“Baby Got Back” by Sir Mix A Lot work for you?

“Get Low” by Lil Jon.

Honestly all these things with sun-puns seem too easy. I’m sure she’d like all these options, but I just can’t help but imagine she’d actually be into something a lot more random and stupid when she’s alone, something maybe a bit embarrassing or ironic.

Land Of Sunshine - Faith No More  
My God Is The Sun - Queens of the Stone Age  
Soak Up The Sun - Sheryl Crow  
The House Of The Rising Sun - The Animals
 
Other options?

@dsagent  
Throws a lunar horseshoe Heretic!

Amazing art!

I really don’t think she’s singing walking on the sun tbh,

Great job!

We’re the kids of Equestria!
 
Oh-oh~ ‘3’
 
We’re the kids of Equestria!
 
Oh-oh~ ‘3’

I’m rather partial to “You Are My Sunshine.”