How did you book your ticket? I generally book with Expedia, and they include the terminal info in the itinerary.

I wouldn't worry too much. I'd expect that at both IAH and DEN your flights will connect in the same terminal. At any rate, you can get the most up-to-date info when you check in for your first flight, and the in-flight mag will have maps of both DEN and IAH if you feel they're really necessary.