With all due respect and I mean that sincerely…
Did you even try what I originally suggested? Once you have your objects selected (which isn’t like you’re moving real concrete blocks around…you’re just selecting objects on a screen*) press M > +Collection > give the new collection a name. That way you’ll never have to select all those objects one by one again, I promise. When you want to select all the objects in that “group” again press SHIFT-G > Collection. And they’re all selected!
CASE IN POINT: Select all the objects in your kitchen scene (which in Blender 2.8 should already be by default in a Collection surprisingly titled “Collection”. Do you see it in the Outliner? Great. With all of your kitchen objects selected press M > +Collection and give the new collection a name. Like “Kitchen”, perhaps. Still with me? If you look at the Outliner you’ll see that you now have a new sub-Collection called “Kitchen”…just like Sketch-Up.
Moving right along, select only your objects which make up your stools and island. Repeat the process, this time naming the new sub-Collection something like “Stools”.
Next, select the objeects that make up a stool (seat, legs, etc.) and repeat the process.
To select all of the objects in a Collection/sub-Collection press SHIFT-G and select…wait for it…Collection.
Now, logically, I would have done all of this in reverse, that is, created a “Stool” Collection, copied it as needed, then selected all of the stools and put them into their own collection…little endian as opposed to big endian.
I don’t think I could have been clearer and I’m 80% sure there’s no faster and easier method for achieving what you’d like to do. If you still are having doubts…well, what can I tell you? Maybe you’re better off in Sketch-Up. Good night and good luck.
(*having problems selecting objects? DId you know Alt-LMB gives you a pop-up menu of all the objects under your pointer? Or if something’s in your way, you can always press H to hide something, SHIFT-H to hide everything except the selected object, then ALT-H to unhide. GT out!)