If you are using Ubuntu and not used to the Unity user interface, the better choice will be gnome-shell. Gnome-shell comes with many extensions that can be added easily. Below are some of the must-have and nice-to-have extensions:

Must-Have:
- AlternateTab
- Alternative Status Menu
- BackSlide
- Bolt
-Disable Window Animations
- No Topleft Hot Corner
- Panel Settings
- Places Status Indicator
- Settings Center
- Status Icon Fixer
- TaskBar
- Weather Indicator

Nice-to-Have:
- Coverflow Alt-Tab
- Dock
- Journal (if you are using the original Gnome Activites instead of Bolt)
- SystemMonitor

You can also remove the maximized windows title bar to give you more working space. Install "Maximus" from Ubuntu Software Center, then run gconf-editor (install this also if you don't have it), and go to apps -> maximus and enable "no_maximize". You will need to logout and login back to get it in effect.