AFAIK with Fargate a lot of this is handled for you, as long as you have the auto scaling group.
We have this setup with two capacity providers (FARGATE_SPOT and FARGATE) with a 75/25% split, meaning that even if there are no spot instances available we will still be up.
The benefit of Fargate being that we don't need to care if certain instance sizes are not available as that is handled by AWS.
Cool, when fargate launched they didn't have a spot possibility (AFAIK) and since we run ECS on Spot instances it would just be a massive increase in cost to switch to FG, but if it now can use underlying spot instances, it might be worth looking at again..
We have this setup with two capacity providers (FARGATE_SPOT and FARGATE) with a 75/25% split, meaning that even if there are no spot instances available we will still be up.
The benefit of Fargate being that we don't need to care if certain instance sizes are not available as that is handled by AWS.