I love the "Matt and Molly" stories: they are in the Autism and PDD series. I like the language ones (have seasonal themes: winter, spring, etc) and the social skills ones. I use them with my regular old language disordered kids from pre K to grade 3 and my moderately intellectually disabled kids grades 3-5 (I can't use the inferencing questions with them, so I add some more basic wh questions). I use "Matt and Molly" to work on sequencing, story retelling, wh questions, yes/no questions, etc.
I have been looking at the Linguisystems website too, wondering if I should take advantage of the sale . . .