I have to say I have totally enjoyed reading this thread. I offer up a big STANDING O to Carlalena for posting the initial topic.

Job well done!!! Now, if you can give us your PayPal ID, we can all send you a nice tip.
I'm Kidding.
Seriously - we must always remember those who provide us service, whether on a cruise ship or in our local restaurant. Spending two summers as a waiter in college, I am very aware of the importance of tipping at the end. That is why when my family goes out to eat, I start with 15% in mind - and as long as my basic needs are met (re-fill my drink, clear my dish when I'm done, and be approachable) I am usually at 20%. It has to be pretty bad service for me to drop below 15%.
So, when my family took our first cruise this past summer on Royal C., we initially looked at the approx. $10 / day / person recommendation as a lot of money. But by day 2, I realized it was nothing. At the end of the cruise, we did the Voucher process the R.C. offers - but we tossed in an additional $20 into the envelopes of our Cabin Stewart, Waiter, and Assistant Waiter, and $10 for the Head Waiter.
Almost from that point I have questioned whether it was enough. Having read this thread, I am still questioning whether I should have put in more.
But like Carlalena, having read so many other posts and complaints about tipping from other posters, I fear that my tossing in some additional money may place me in the minority.
Thanks to everyone on this thread. There is some very interesting things to think about.