Since I can only vote for 1 as answer, is commenting on all good answers with thanks considered filling the site with chatter?
MariBar
You can vote 30 times per UTC day, plus 10 more times on questions only.
http://libraries.stackexchange.com/privileges/vote-up
I'd recommend waiting a day to come back to the answers you'd like to vote. You can also cancel votes by clicking on the upvote or downvote button again.
Remember, marking a question as the accepted answer is not the same as voting on answers, you can only mark one answer as accepted and this can be cancelled or changed any time unlike voting which can get 'locked in' after a certain amount of time.
Unless you have something valuable you can contribute to the answer it's best not to comment. But it's acceptable to thank somebody in a comment in addition to making a point (even if that's nothing more than explaining how you found the answer useful).