We did 4 weeks Sri Lanka in 2019. If we would go again we would only stay at the Ceylon properties.
Amangalla is ok, in general we have very good esperiences with Aman, but Ceylon teavtrails is just better imho and Galle is not really interesting, very touristy

Anantara peace heaven was not ok, however we stayed there to save costs.

Tea Trails is one of the best hotels ever for us ( we stayed 5 nights which is perfect)

Wild coast tented lodge is amazing for 2 nights ( we took 3 which is too long)

If you are looking for a good hotel that is more affordable I would advise Ulagalle resort Thirappane. We loved it. It’s not expensive but the food and service are just soso.

Near the airport I would recommend The Walauwa , It’s an amazing place to stay a last night before you head back to the airport.

For 8 nights I would do:
4 hour drive
- 3 nights Tea trails
7 hour drive
- 2 nights Wild coast
3 hour drive
- 3 nights Cape Weligama
2 hour drive

it’s easy to visit Galle from Cape Weligama and to lunch in the Aman if you really need to see it.