I'll put Your Place or Galanga Thai in Santa Barbara against any Thai. I haven't tried Lotus of Siam in Las Vegas, but I've been to Thai Nakorn in Garden Grove and others in L.A. as well as Thai restaurants from Vancouver to San Diego. These two in Santa Barbara are both excellent choices. They both make two of the best Tom Kah Kai's I've ever had. The only caveat I'll add is that Your Place seems to be better at dinner than for lunch; just my opinion.
I personally like "Your Choice" which is on upper State Street near Las Positas. And the "Zen Thai" (name?) on lower State Street just recently got reviewed in the local paper - which is also a good choice.
Agree, the Thai is very standard here but that doesn't mean you will not find some favorite dishes at each of the restaurants regardless. And Your Place on Milpas is indeed a popular and good choice too. It always is the award winner for Thai food in Santa Barbara.
I find myself sticking to Pad Thai a lot which is the dish I use to measure a restuarant. And any place that makes mee grob is a hit with me too. That is one reason I have liked the one on Upper State near Las Positas - musching mee grob and a beef salad together on the same plate was a surprising flavor and texture treat for me.
There are several Thai restaurants and often a Thai cooking class with the SBCC Adult Ed program that you might also want to try since there are several good asian markets also in town - more out towards Goleta.
And again I'll toss in driving to Ventura for "Mai's" on Main Street for Vietnamese/Hawaiian if you are in a SEA mood.