I got the bus out to Lyttelton and walked over the tops to Sumner, is a nice walk. Could do the gondola/cable car on the way.
Walk along the parade and some nice shops at New Brighton.
The art gallery is decent.
There’s a good sandwich shop/cheesemongers, where you go in and pick your cheese.
If you can get down to Akaroa, I would recommend it.
Friends live there so will ask them if there’s anything special on this week.