Yeah, Kapt Kopter is interesting. Not sure it's a GREAT album, but worth a few dollars if you can find it.
You should get Clear and 'Family' to round out the collection, for sure. Clear is a little more jazzy than the others and 'Family' has their classic tune "I Got a Line on You".
Spirit of '84 is interesting - recorded in '82, they re-recorded many of their early tunes plus a few new ones. It's actually pretty good.
The first Jo Jo Gunne album is a must-have, if you like the rockin' side of Spirit.