I've got a few questions where I think the best answer is all of the answers, there's not really one that stands out. Should anything be done to those? or should they simply be left without an accepted answer. Here's 2 of them
You have several options:
Accept an answer you like more than the others. This is particularly useful if you're asking a question about a situation in your game, and you choose one answer among them to be the ruling/idea you use in your game.
Accept an answer, and bounty one or several of the other answers. You can always add bounties to questions you or someone else has asked, each bounty you add has to be an increased point value.
Do nothing. You don't have to accept an answer, and no one can make you do so.
Add a new answer that incorporates the best of all of the other answers.
The important thing here is that the criteria for an accepted answer is best, most useful answer. It's completely your call, so do what feels right to you.