I've been to the Six Flags Over Texas Holiday in the Park many times. My family loves going, but not for the same reasons they like to go to SDC.
The Holiday shows at Six Flags do not compare to the ones at SDC. The lights at Six Flags are not on the same level as SDC. Six Flags will have some very nice areas, and has the snow hill, but the park on a whole is no where close to the production SDC puts on. I do like all the holiday food booths that Six Flags sets up, but SDC's food is already good.....The difference is Six Flags brings out a lot of holiday favorites and specialties that are really good.
The area where I think Six Flags totally fails is with their shops. I love to shop SDC at Christmas time. I've spent several hundreds at SDC during Christmas, but have yet to buy much of anything at Six Flags.
Also, during Holiday in the Park at Six Flags not all the park is open......
Jay