The main drag of Rothesay does look a bit bedraggled, but we really enjoy the island as a whole.
You must go to Mount Stuart, it is fabulous, so interesting, You need to book, but the last time I was there you could book at the venue so no real issue there. Groups are taken in and given a tour together. It has extensive gardens reaching down to the sea. Great for walks.
Walk up the Serpentine just off the main street and eventually come to Canada Hill, where people would go to wave off people heading for America. Great views (walk takes you through a golf course, keep going and you can loop round back to the top of the hill, looking down at the bay.)
You can take the bus down to Ettrick bay, only a few miles, and have long beach walk, see seals. Take binoculars. Great views of Arran, and maybe some other islands. Or get off the bus at the graveyard and walk down to the bay using the little path which used to be a tram way. Maybe 20 mins. There is a great tea room on the shore. Hot food and good cakes.
If you have a car, there are other good empty beaches to stroll on, and there is a very atmospheric St. Blane's Chapel which is a ruin in a quite circular site, very medieval.
Scalpsie Bay also for seals and a good stroll.
Kingarth Hotel does great lunch.
There's the renowned men's Victorian toilets at the quay.
You can take the small ferry over to Colintraive (10 mins) to a good hotel for lunch.
There are a few 'nice stuff' shops in the town, but not great for that sort of thing.
Two Zavaroni tearooms.
A castle - never been in it.
Remember to look at the Glenburn Hotel is you pass it - amazing Victorian majestic building.
Cinema on sea front, plus gift shop with some lovely things
Other walks too that I cant remember, you would need to check detail.
Nothing in Port Bannatyne apart from boats I think.
I've gone on a bit - some people will like the place, some wont!