The Blind extrude dimension doesn't show for me when creating the feature either. However, after closing the feature you can click on it in the tree (or double-click if you don't have Instant 3d turned on). That will display the dimension in the graphics area where you can select it to add to design tables, link to custom properties or global variables, etc.
Another option is to right-click on "Annotations" at the top of the tree and choose "Show Feature Dimensions" from the drop-down, but for complex Parts this can add so much information that it's difficult to sort out the right dimension.
Thanks for the response. That's what I needed to know. Double clicking on the feature was the trick.
I think I had stumbled across the annotations folder once a few weeks ago, and forgot about it.
I learned something today, I guess I can go back home now.