25 Years Old
"Do you know that you can save 15% by switching to Geico?"
"15 minutes could save you 15% or more on car insurance."
Geico has advertised that switching to them will save you money. Other car insurance companies market that they can do the same. In theory, you can continuous switch and eventually have almost free car insurance. But, of course, this is not how it works.
Since most companies spend most of their resources focused in getting new customers (e.g. Comcast), it's refreshing to see companies offer loyalty benefits for their existing customer base. I personally experience loyalty benefits every time I pay my families' T-Mobile bill; it's ridiculous low for unlimited Internet since we've been with them since Voicestream.
Today, I felt more company loyalty benefits; this time from Progressive. My car insurance policy cost went down 20%. That's 20% lower without having to go through the effort of switching companies. The drop in cost is probably due to turning 25 years old and transitioning into a Platinum Membership by being with Progressive for 3 years.

I can't wait to take advantage of the Minor Child Discount... Muhahaha (It's funny because that's not going to be for quite a while). Maybe I'm a sucker for achievements, but I can't wait to become a Crown member!
What other companies reward their loyal customers?