I really like jQuery because it's lightweight but I think it really fits your needs perfectly. For DOM manipulation in jQuery you just use CSS selectors, so... :

    $('a.hide_these').hide();

Would hide all anchors with class 'hide_these'. You don't have to do any iterations or pass any anonymous functions. Traversing works the same way too:

    $('a.hide_these').parents('p')

Would find all the paragraph tags that are parents to those anchors.

I've only used a few animations from jQuery (like sliding/fading) but the framework also lets you do your own custom animations using CSS (your element will gradually morph to the styles you define).