Do you pay attention to how you sign off emails?

For long I have observed the way people sign off their corporate emails. I have come across all sorts - the silos (Regards, Thanks, Best, Cheers, Sincerely), the extra polite ones (Warm Regards, Many thanks, Warmest Regards, Kind Regards, Best Regards et al) and then the falling-on-your-knees ones (Thanks and Regards, Thanks and Warm Regards, Many Thanks and Warm Regards etc.). The one that I particularly like are the abbreviated ones - thks, rgds, thks and rgds etc. How much effort is it to type "regards" instead of rgds?  And that too when you have an auto sign off so you are not even typing it every time. And why write both "thanks and regards"? Isn't one enough? Thanks/Sam or Regards/Sam works just fine, I think. Either way, I feel no one really cares as long as you write something - thanks/regards/warm regards. Someone I knew very well used to write 'many thanks'. This I used to find particularly funny because I don't understand what is 'many' thanks. Are  you standing there and singing thank you? Or are you going on saying thanks till the other person asks you to stop. Can you imagine how confusing it is, how much is many? 2 or 4 or more than 10!
And I once came across "Many thanks and Kind Regards". I felt the person was literally on his knees thanking me at the end of the email, all the while giving me a status update of some project. I mean, why many thanks when I haven't done anything for you that needs thanking. 

So what is the ideal sign off? I feel "Best/Sam or Regards/Sam" is quite professional and to the point. Doesn't say more than what is necessary and is not rude too. Depending on whether you actually want to thank the person you are writing to, you may use Thanks/X. And remember, if you have put an auto-sign off, then it looks quite unprofessional to have Regards/Sam and then right below, Thanks and Regards/Sam Manohar. So how do you sign-off? 

Many Thanks and Warmest Regards

Harish