I'm of the growing opinion that the elegance of functionality and balance between DLs, SLs, DLVPs and SLVPs is becoming more and more corrupted.
It appears that there is no correct & comprehensive way to dimension a project.
Annotations in SLVPs seemed at one point to be where most dimensioning would eventually live. However, 3d dimensioning is now confined to Design Layers, (as are 3d annotations) The Auto-dimension walls command still only works on a design layer and any dimensioning created on a SLVP are not useful when working on the model.
Dimensioning on a Design Layer leads to clutter & scaling issues.
I had a dream where all dimensions would live in a SLVP as an annotation,
where 2d, 3d and auto-wall dimensions could be created as an annotation
where the SLVP would know, upon invoking the dimension tool, that an annotation was coming - and forgo the redundant q&a required to edit the Viewport Annotation (I know it can be set as a preference)
where dimensions created on a Design layer could be automatically sent to join the SLVP Annotations,
where annotations could be selectively ghosted and usefully displayed on the Design Layer
and where pressing the key combinations n-5, n-2, n-6 would automatically place dimensions on planes parallel to the x-y, x-z and y-z respectively.
Of course a 2 cursor system might be needed to keep the information from becoming overwhelming in the DL and a way to selectively display the available project dimensions on each viewport would need to be incorporated.
In the meantime - I'm liking Ray's idea more to "dimension on the design layer when possible, in annotations when I can't."