I just read the tipping advice at the Disney Food Blog and there is some erroneous info. So I just thought I'd toss out what I know.
Tipping has not climbed to 18%. What has happened is that tax on meals has become nearly universal, and most people just tip on the bottom line. The thing is that no tip on tax is necessary in any way. So 15% of 8% adds another 1% or so, and then if you round up it can become 18% of the pre tax bill easily.
On the flip side, we love eating at little old fashioned breakfast spots. Sometimes the bill for 3 comes to $15. The minimum appropriate tip is $1 per person. If the waitstaff has been especially diligent refilling water and coffee you ought to add a $1.
Finally, I noticed that WDW will recommend an 18% tip at their buffet restaurants. I'm not sure if it's on purpose, or just a STD computer code for all on site table service receipts. But thats a big tip for a server who doesn't take your order for anything besides beverages, doesn't bring any food. And from what I can tell doesn't have a bus staff to split it with (yup typically the bus staff gets from 1/3 to 1/2 of all tips). My feeling is that 10% (or about $4 per person) is adequate, 15% is generous. But this is JMO.