It sounds like you're doing plenty to me!
I'm wondering if interest can be piqued using your wheelchair walk - maybe this isn't logistically possible - but what about tourist information leaflets? Maybe if your wife had a pile of leaflets with lots of pictures but not may words she'd like to look through them and choose somewhere to go. We find that lots of tourist places let carers in for free, so it perhaps matters less if you don't spend long there. We had a particularly lovely day out at a zoo a couple of years ago, we'd not considered going since the kids were small but really enjoyed watching the animals and we were having little 'conversations' about it for ages afterwards.
We splash out on National Trust membership every year as they have lovely gardens and tea shops and parts of many houses are accessible.
These aren't things that you could do every week but maybe one day trip a month with some planning time in between??
Or, what about car boot sales and charity shops? Just pottering round to see if a game/jigsaw/activity would interest your wife, maybe it wouldn't cost much and so if it's not used much wouldn't matter and might be easily replaced.
Has your wife tried crafting, making art or just doodling? I'm wondering if making something herself would keep her more interested than watching or listening to something she's not part of. You might need to be creative with keeping paper still and pots upright but after 8 years I bet you're the king of finding ways around!
We recently went to a 'friendship club' to represent the stroke association at their Sip for Stroke, it was the most wonderful atmosphere, everyone was having a little gossip or just watching the others and we all did arm chair aerobics, which was good fun. I wonder if your wife (or you!) would enjoy a club like that.
We've not been doing life after stroke half as long as you, but one thing that I had to learn was to be open minded to new ideas, to question what other people do with their time and consider trying things - our life before stroke didn't involve sitting still ever so the idea of going to the cinema took some getting used to! It would be lovely if our stroke community could post what we all do, the smallest things can bring such pleasure! For example, on Tuesday we're going to Cambridge Beer Festival to try a few halves and watch the world go by, simple but definitely a highlight of May!
I try to get something on the calendar each week to look forward to - I wonder if your wife could be inspired by filling a calendar - or completing a diary with photos and mementos.
What do you think of those thoughts? Might any show promise?