Allyson,

You can save your Excel data in three columns (x,y,z) as a '.csv' (comma-separated-values) file. Excel produces a text file containing your x,y,z data.

The .csv file can be imported into SketchUp, by use of Didier Bur's 'Cloud_V6' plugin, available here:
http://www.crai.archi.fr/RubyLibraryDepot/Ruby/en_fil_page.htm

Note that this plugin will create a guidepoint at each x,y,z location. It can 'skin' the surface, if it's relatively horizontal (such as a topographic surface.) If you have any vertical faces, or 'bottom' faces, or vertices that are 'stacked' over another, the skinning won't work properly. I use the plugin to import vertices for geodesic spheres, and manually connect the data points with the 'line' tool.

Epcot_Spaceship_Earth.png
If you have faces that are vertical, or 'beyond' vertical (undercut,) you likely will have to do some manual line connections yourself. Hopefully, this method will give you the start you need.

Taff