One of the patterns looks like it requires more processing power than necessary. The rendering of a template should be fast, since you will likely be doing it many times on a page.

    ContactView = Backbone.View.extend({
      template: function() {
        var template = _.template($("#template-contact").html());
        return template.apply(this, arguments);
      },

      render: function() {
        // This is a dictionary object of the attributes of the models.
        // => { name: "Jason", email: "[email protected]" }
        var dict = this.model.toJSON();

        // Pass this object onto the template function.
        // This returns an HTML string.
        var html = this.template(dict);

        // Append the result to the view's element.
        $(this.el).append(html);

        // ...
      }
    })

Note that the template is already on the page and has to be serialized by jQuery with the `_.template($("#template-contact").html());` line. It would be faster to already have the template in a JavaScript string, ready to be interpolated with your values.

Otherwise, for every view you will be fetching the template from the DOM. The difference in implementation would be from this:

  <div id="template-contact">Mail me at <%= email %></div>

to this:

  <script>var templateContact = "Mail me at <%= email %>"</script>

It's a bit more work, but it reduces the amount of work that has to happen just to render one of many templates.