If you find an answer satisfactory and it answers all possible questions that pop up in your mind go ahead and select it as the best answer. According to the forums, there may be an option to change best answer later on as people may misuse it just for the accolades.
Accolades give hubbers no benefit other than some temporary joy, so I doubt it actually makes a difference when you choose a best answer. If people are really interested in answering no matter what, they'd answer it. Even if you already picked a best answer.