Senior palates often prefer flavours they grew up with. Tender coconut sponge with a light condensed-milk frosting feels like a familiar dessert without being heavy. Rose pistachio, especially in eggless form, is a perennial choice for North Indian and Bengali families.
Filter coffee buttercream works for South Indian grandparents — the bitter-sweet balance is one most have tasted in mid-afternoon at someone's home for decades.
We steer people away from: very dark chocolate (above 70% cocoa, often too bitter and intense), heavy fondant exteriors (most seniors will cut off the fondant and leave it on the plate), and very rich cream-cheese frostings on dense cakes (uncomfortably filling).
Size matters too. A 1 kg cake for a 25-person family gathering is right because the older guests will eat smaller slices and there will be leftovers for the next morning's tea anyway.
If the celebration is for diabetic seniors, we make a 40%-reduced-sugar version that still feels celebratory. Notice required is 48 hours.