We are entering the final week or two for many Ironman athletes, with Arizona this Sunday, and Cozumel the following. Some athletes I consult with by reviewing the program they write themselves, and I give feedback on that. When it comes to tapering, it can be as much art as science. Many athletes struggle to find the balance of what is enough, what is too much.
Here's a tip for tapering for Ironman; if you are going to risk overdoing the volume, make sure it is more on the bike than the run. If you really want to do more, add more bike volume, do less run volume. Running in general poses more risk of injury, and requires more recovery time. For example, instead of doing a 90 min run 1 week out from the race, do 60 mins and then add some bike time, say 30-90 mins spin afterward.
Best of luck!