The most important thing that I've found with Seniorboy is to give him small and often - keeping the food fresh and varying the flavours with every meal. (About half a pouch at one sitting so the fridge always has two or three part pouches in it of different flavours being rotated.) He gets bored with tastes very quickly.
As he's pretty old now (how old is your girl?) I'm also more liberal with food types than I would be with a younger cat. Unless something is actively bad for him, he'll get a taste of something if he shows signs of fancying it with my main concern being to get useful calories into him. (Bits of chopped up rare roast or grilled meat are a big favourite along with the meat juices with the fat skimmed off.) Most of his food is still commercial wet food because of the nutritional balance.
He's doing pretty well on that mix. Losing a little weight every vet visit but no more than might be expected with an elderly cat.
Until recently I had 2 very elderly cats (17/18 years old) and they adored Feline Fayre food (available from Asda and also often found cheaper in Home Bargains/Quality Save). Their favourite was the Tuna white meat with prawns in jelly. There is a high fish content (around 50%) and it does look just like a tin of tuna for human consumption.
I also gave them James Wellbeloved cereal-free dried food as this seemed a bit easier on the guts of one of them