I think I may have answered my own question, because I see that I can't add spot els to an Xref. Or can I? What happens is I specify the point and it gives me a leader, but there's no elevation.

David,

It sure sounds like you need to watch this Power Tip video.

--J

Yes. I watched that and have done it with other drawings successfully. 

However, in this job, I haven't added the spot elevations yet. When I try to add them to my Xref'd base map. I get an Mleader, but no elevation. 

David,

Are you sure the elevation is just not very, very tiny?  It could be that you have not set a scale.

--J

<--- This is where I paste a photo of me with a sheepish look. Yep. It was there all along. Very tiny because I hadn't set the scale.

But just to confirm, YES, I should make those spot elevations on a separate DWG. That way, it will be easier to create a digital elevation model in SketchUp. 

Thanks!