Great series, thanks for posting it.
Something to keep in mind is that you can use the Resource Governor to specify a MAXDOP for a Workload Group. Which will override the system default, and set a maximum for the MAXDOP hint in queries. I think that it would be a good way to go for OLTP systems, where you can put the OLTP transactions in their own workgroup with MAXDOP set to a low number, and still allow other queries to take advantage of the parallelism.