Hi,
If you take it to Infinity, ask for the runout on the discs to be measured with the wheels torqued on.
Then ask them to measure the runout with the wheels off but the disc trapped on the hub with 5 nuts not 2 as is standard in dealerships.
If the readings are very different the chances are you have an issue with the wheels.
In this instance changing the discs alone or skimming will only alleviate the problem for 1500 to 2000 milles before it reappears.
Try the Italian tune up as suggested, this can in some cases help, it will soon become obvious whether this is helping. If the judder becomes worse every time you do the tune up it ain't going to cure it.