MTed, (...but you have to keep in mind that you have create a program that is important to the grantor--it is their money. after all...)  Duh...
(You can say the same for anything you're selling--it has to meet the buyer's need/wants -- even if you have to make them aware that they need/want it.)

Question is, how/where can you find out about such potential grants?

Marion,
Among the "senior" places that hire me to do music are:
¥  (drop in) senior centers ( folks go there to socialize, not to get help with ADLs)
¥  adult day care centers (for folks who need supervision during the day for mental or physical reasons or both)
¥  group homes (for behavior disordered, drug rehab, developmentally challenged, geriatric, etc. people)
¥  geropsychicatric units within hospitals
¥  convalescent/rehabilitation facilites (with both long-termp patients-e.g., frail elderly and MS/CP patients-- and short-term patients--e.g., head injury, neck and back injury, and hip-fracture patients) and often with a wing for the memory impaired (e.g., Alzheimer's patients)
¥ nursing homes that house only the frail elderly (in need of 24 hour care for physical and/or mental dysfunction)
¥ assisted living residences (folks who need lower levels of care/supervision for physical or mental conditions or both --e.g., folks who need help bathing, folks who need daily medications monitored by a nurse, folks whose short-term memory deficits necessitate supervision)
¥ independent living residences (for people who need little or no assistance with their ADLs but who prefer the option of having their meals and housekeeping provided and having the social opportunities available in a community of senior citizens)
¥ retirement communities (with a range of lifestyles, including private homes, condominiums, apartments, residential group facilities, etc., all in the same complex)

Some of these types of facilities have mixed-age populations, and even in "senior" facilities, there may be several generations present for a program (with staff, children, grandchildren, and great-grandchildren of residents attending/participating in some programs).

Also, some facilities are specialized populations, such as Jewish homes, Christian church-affiliated homes, Hispanic-related facilities.

Pictures and CDs are usually not necessary, but it "couldnt hoit" to have them available for the activity directors who want them.  It's more important to have a brochure/flyer that tells what kind of music you do  (e.g., jazz piano, folk guitar, classical banjo) and how to contact you.  You can give more information when you talk to the activity director.

Don't assume that anyone has a decent PA system.  Some do, but others have none at all.  I use a Fender Amp Can for jobs where I need a little amplification but don't need to have concert-hall sound quality.  For very small rooms or 1-to-1 music therapy, I use no amp.  I have more cumbersome but better quality amps for when I really want to fill a room and sound my best.  One thing you should know is that when playing at nursing and convalescent homes, you will very often be interrupted by PA announcements, nurses shouting in residents' ears to administer meds,  sometimes disruptive residents, and--oh, yes-- family and staff members carrying on loud conversations as though there were no activity going on at all!  Do invest in some sort of small PA system unless you're a belter and have a loud instrument, too.   I don't charge differently based on the PA system per se, but I do offer reduced rates to LOW BUDGET facilities if I can do the gig there--all things considered--relatively easily, conveniently, and quickly.

Genie