When short term memory deficits set in, folks tend eventually to recall little except from early childhood, so if my clients are over 90, I try to use songs that either are simple or would have been learned when they were children.  (Note:  It's not all that unusual for some of them to remember all the verses to hymns that they learned as youngsters.)  Younger audiences (75 to 90-ish) and folks with significantly less cognitive impairment tend to know the words to a lot of songs they sang as teenagers or young adults and often are especially partial to the tunes from their courtship days.  (Don't forget that in most nursing homes, there's about a 15 to 20 year age spread even within the "main" population.  Some were 'weaned' on turn-of-the-century songs and others on songs from the roaring twenties.)

If a song is very catchy, energizes folks, and has an easy chorus, it doesn't matter too much how old it is. (See the list at the bottom.)

Here are some examples of songs I find go over very well as sing-alongs for various types of facilities.

Alzheimer's facilities:

My Bonnie
Clementine
Down In The Valley
Red River Valley
I've Been Working On The Railroad
Take Me Out To The Ball Game
Jesus Loves Me*/He's Got The Whole World In His Hands
My Wild Irish Rose
Home On The Range
Oh, Susanna
Moonlight Bay
She'll Be Comin' 'Round The Mountain
I'm Looking Over A Four-Leaf Clover
Comin' Thru The Rye
Bicycle Built For Two
School Days
Sidewalks Of New York
Pack Up Your Troubles
There's A Long, Long Trail A Winding
Old MacDonald
 
 

Assisted Living facilties

Always
It Had To Be You
Sentimental Journey
How Great Thou Art
Have I Told You Lately That I Love You?
Red Sails In The Sunset
My Old Kentucky Home
Danny Boy
Blue Hawaii
My Blue Heaven
Blueberry Hill
Tennessee Waltz
Edelweiss
Yankee Doodle Boy/You're A Grand Old Flag
God Bless America
Please Release Me
The Glory Of Love
Just A Closer Walk With Thee
Java Jive
Georgia
Goodnight, Irene
Michael, Row The Boat Ashore
For Me And My Gal
Three Little Fishes
On The Sunny Side Of The Street
Don't Fence Me In
I Love You Truly
All Of Me
Any Time
Nevertheless
Besame Mucho
Hey, Good Lookin'
Your Cheatin' Heart
I'm An Ol' Cowhand
 
 
 

Both Memory Impaired and Assisted Living sing-alongs:

Oh, What A Beautiful Morning!
Springtime In The Rockies
In The Garden
Side By Side
You Are My Sunshine
Let Me Call You Sweetheart
Baby Face
Yes Sir, That's My Baby
America The Beautiful
Let The Rest Of The World Go By/Till We Meet Again
Too Ra Loo Ra Loo Ral
Shine On, Harvest Moon
Home On The Range

La Bamba
Three Little Fishes
Doggie In The Window
Proud Mary
Wimoweh