So, thank goodness you can turn that nonsense off in Gmail and if you want an even more clean and simple interface (which in some cases, does mean less "functionality"), try these tips.
1. Turn off conversation view
Settings: General: Turn the conversation view off (you'll still the conversations just not as a thread)
2. Hide what you don't need.
- Settings: General: Hide Send & Archive Button
- Settings: Labels: Hide anything that is unimportant (or perhaps, not active or critical)
3. Change buttons to text (Settings: General)
4. Turn off the people widget (Settings: General)
5. Get rid of snippets (Settings: General)
6. Minimize your inbox - limit the number of posts to a page (Settings: General)
- Limit the number of conversations on a page (choice 10-100)
7. Organize your inbox
- Settings: Inbox : Set inbox type (choice of Important First, Unread First, Starred First, or Priority Inbox)
- The default is your tabs> Remove tabs and you will have a traditional chronological listing
- Priority Inbox is "important, unread, and starred inboxes and adds more customization options" (customized options include specific labels> see More options).
- Filter! Settings: Filter - setup! (also, you may be able to change some of these at the subscription level - like the twitter notifications...
8. Tighten up settings for other things: (if you use Chat, then make sure take a look at those settings as well.
9. Finally, make it pretty! (Settings: Themes)