Terraform Enterprise in a multi zone environment

Hi together,

we manage our infrastructure in AWS of course with Terraform. Since our needs grow and we want become more mature with regards to collaborating we plan to implement Terraform Enterprise.

However, in the concept phase we struggle with the following issue:
Our setup looks like:

├── dev
│ ├── zone1.tfvars
│ ├── zone2.tfvars
│ └── zone3.tfvars
├── main.tf
├── outputs.tf
├── prod
│ └── prod.tfvars
├── qa
│ ├── zone1_qa.tfvars
│ ├── zone2_qa.tfvars
│ └── zone3_qa.tfvars
└── variables.tf

At the moment people deploy like this:

$ terraform plan -var-file=dev/zone1.tfvars -out myplan 
# extra state file
$ terraform apply myplan

# or

$ terraform plan -var-file=dev/zone2.tfvars -out myplan 
# also extra state file
$ terraform apply myplan

People want to decide which zone they deploy.

I though about workspaces for each zone, but then we would end up with around 20 workspaces.

What may be other approaches?