Well, after I don't know how many fits and starts, snags and snafus, ups and downs, and a whole lot of frustration, I can honestly say the pieces and parts are actually starting to look like some kind of a tabletop.
In order to get the right dimensions, things had to be laid out - sort of. The end and side pieces are, of course, still too long, but this photo at least gives an idea of what it should look like when glued up - hopefully.
Now a decision needs to be made - do I just go ahead and fill the gap with another juniper piece the way it is and leave it offset (one cottonwood slab is wider than the other). Or, do I glue-up the cottonwood slabs and then cut the one slab right down the middle to get two identical sized slabs on either side of the center piece? One way or the other, this is a necessary step in order to get the desired width of the tabletop of 36". Otherwise, the cottonwood slabs would have just been glued together and used for the center piece which would have left the width about 5-6" too short.
After much deliberation, contemplation, meditation, and soul-searching, my linear side won out - glue them up and cut right down the middle.
After all the pieces and parts are kind of cut to length, it's time to see if the dimensions are even close to being what they need to be. Width - not quite 36" wide, but close enough since this measurement was taken at the narrowest point of the natural edge.
Length - well, doggone it! It's a little longer than 48", but that's ok, too, since additional sanding and trimming will bring it closer when finished.
This is what it looks like with the juniper piece down the middle and two equal size cottonwood slabs on each side. All the pieces and parts numbered (gotta remember which pieces go to what parts, don'tcha know) and getting closer to glue-up.
Dang! It really IS starting to look like a tabletop. Now the sanding, trimming, grinding, and sawdust making begins in earnest!
Still have the pedestals to work on, and am thinking that might be something to do while waiting for the glue to dry once I get started on glue-up.