There are some great ideas here, and I can't think of any better musical selections. The most adorable and witty piece I ever heard at a wedding was a reading of the poem "Tin Wedding Whistle" by Ogden Nash. If there were a song that captured that poem's essence, I'd say go with that song.
Though you know it anyhow
Listen to me, darling, now,
Proving what I need not prove
How I know I love you, love.
Near and far, near and far,
I am happy where you are;
Likewise I have never larnt
How to be it where you aren't.
Far and wide, far and wide,
I can walk with you beside;
Furthermore, I tell you what,
I sit and sulk where you are not.
Visitors remark my frown
Where you're upstairs and I am down,
Yes, and I'm afraid I pout
When I'm indoors and you are out;
But how contentedly I view
Any room containing you.
In fact I care not where you be,
Just as long as it's with me.
In all your absences I glimpse
Fire and flood and trolls and imps.
Is your train a minute slothful?
I goad the stationmaster wrothful.
When with friends to bridge you drive
I never know if you're alive,
And when you linger late in shops
I long to telephone the cops.
Yet how worth the waiting for,
To see you coming through the door.
Somehow, I can be complacent
Never but with you adjacent.
Near and far, near and far,
I am happy where you are;
Likewise I have never larnt
How to be it where you aren't.
Then grudge me not my fond endeavor,
To hold you in my sight forever;
Let none, not even you, disparage
Such a valid reason for a marriage.
