Displays full content for first 2 posts, excerpts for the rest

genesis-category-template-2-full-posts.php

<?php 

remove_action('genesis_post_content', 'genesis_do_post_content');
add_action('genesis_post_content', 'custom_post_content');

function custom_post_content() {
	global $loop_counter;

	if( absint($loop_counter) < 3 ) {
		the_content(); ?>
		<?php }
	else {
		the_excerpt();
	}
}

genesis();