Terms become easier to discuss when people stop pretending every preference is nonnegotiable.

Treating every preference as a requirement makes agreement impossible and everyone knows it, which is why nobody believes the claim after the first few. Being honest about which items are firm and which are merely preferred speeds everything up and makes your firm items credible. Blanket rigidity is a way of hiding priorities and it costs you the ones that matter.

Before any discussion, mark your list into must, prefer, and would be nice. Say which is which when it helps. Being clear about flexibility is what buys you seriousness where you are not flexible.