Offer Negotiation beyond salary, money etc

Vacation, start date, sign on, etc

I've heard two things about the "negotiate extras" line of reasoning: 1) it's a great way to get more stuff when they won't budge on salary or 2) the added difficulty of doing per-employee exceptions (E.g. Special vacation accrual rates) means that it's a no-go or huge pain

Ability to work remotely more often is the big one for me. You can negotiate for literally anything, but you may have more success with things that your manager could easily approve, as opposed to things that would require exceptions to corporate policies.