I do this all the time and I'm still about to find one plugin that covers all the ground.
( That would be the Holy Grail... hey, that's a good name for a plugin! :) )
This is what I use to have enhanced, controlled and minimalistic Admin UIs:
- Adminimize: CSS hiding of large chunks of the Admin with role filtering. Custom roles are also listed. You can declare custom rules in Your Own Options.
- To really block (or give) user capabilities: User Role Editor or Members
- For giving another flavor to the Menu, Ozh' Admin Drop Down Menu coupled with Admin Menus Fixed
- This one is quite nice for hiding all the Help Texts: Admin Expert Mode. But it is very specific, and I ended up incorporating its CSS (due credited) into my own plugin (bellow).
And there's a last one that I wrote, Many Tips Together.
And if you allow me, a brief history:
Adminimize was not enough for my goals. And I had a private plugin with a collection of functions for dealing with many other little hacks, like the ones found in is this wonderful post: Best Collection of Code for your functions.php file
Finally, I made an interface and released it.
Version 1 grew immensely and there are hundred plus options to play with. It is fairly decent coded, but I cannot be sure until not sitting down and reading this book: Professional WordPress Plugin Development. Caveat emptor.
So, in every site I do, this four are always there: Adminimize, Ozh+Fixed and Many Tips. The role management goes case by case. And normally I have a plugin - /wp-content/mu-plugins/site-name.php - where I drop site specific functions.
Just found a brilliant WPSE plugin for dealing with all your custom translations needs:
Retranslate, by toscho