I would not set the RewriteBase unless your on a system like Rackspace which requires it. In that case I would set it too /
This is so that it will default to the base directory.
Here is the .htaccess file I use. This way when you go to mypage.com/uri whatever you put as uri is the controller that is called
Options +FollowSymlinks
RewriteEngine on
# On Rackspace and getting 404's? Uncoment this by removing the # :
# RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
<IfModule mod_rewrite.c>
RewriteRule ^(.+)\.(\d+)\.(js|css|png|jpg|gif)$ $1.$3 [L]
</IfModule>
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L]