A western theme cake and maybe a six shooter quick draw contest between a few staff members would be fun if you have the props. Music and props and interactivity by the staff make the party.
Of course, you invite all of the residents and maybe families, as well.
Many old western songs are remarkably well known so you can get a fantastic sing-a-long going.
A nice touch is using western theme napkins and plates and or table clothes.
I like the party favors and props because they really give it a nice distinctive touch.
This works well with residents who are in nursing homes, assisted living facilities, independent living facilities, who have dementia and Alzheimer's, as well as seniors who live at home.
I like to call my country western show "Songs Of The Old West".