Have you used the admin_menu module? It replaces the regular administration menu block and is a must for anything Drupal 6 or less. Drupal 7 has a built in Admin Menu that is very similar to the aforementioned module and it really makes navigating through the administrative areas a much nicer task.
Also for Drupal, I have been a fan of TinyTinyMCE however, I'm now a big fan of the WYSIWYG module. What I like about this module is that is is a wrapper for TinyMCE, FCKEditor and several others. You install the module and then put CKEditor, FCKeditor, jWysiwyg, markItUp, NicEdit, openWYSIWYG, TinyMCE, Whizzywig, WYMeditor, YUI editor, etc... in "sites/all/libraries" then you can configure your editor. Best of all, you don't have to write or edit an init script to add or remove icons from your editor. Well worth a try IMO.
Other than that, I would recommend taking D7 out for a spin. It's set to release any day now and since Drupal is built to manage multiple sites right from the get go, I can't imagine why you would look anywhere else.
Let me know if you'd like to take a vanilla copy of D7 for a spin... I have a copy of RC2 running on a test server and I can set up an admin role for you to try it out with.
EDIT: Some links regarding multiple sites and multisite:
http://gotdrupal.com/videos/multisites-vs-multiple-sites (comparison multisite vs. multiple sites)