Need better wifi coverage

OK, I have a TRI-LEVEL home.  For many reasons, I would love to change that, but it just isn't in the cards.  When I say TRI-LEVEL, there are actually 4 levels.  A basement (concrete walls and where my cable comes in), the next level up "Family room" (Concrete floor and off to the left of the basement), then the main level (sits above the basebment), and the 4th floor which are the bedrooms which are above the Family room).  I have the R9000 on top of our kichen cabinets (much to the displeasure of my wife) and I have the EX8000 on the far end of the Family room, which is the next level down from the Main Level (Kitchen).  I have a Switch in the basement which feeds all the wired jacks in my house.  I'm using the EX8000 as an AP, not the mesh system.  I started with the mesh form of that, but it didn't seem to work well.  As an AP, it is slightly better IF you are in the Family room.  Bascially, the Family Room and Main level have DECENT wifi, but the other 2 levels suck. 

Can something be added to the existing stuff to get better coverage in the basement and 4th level, or do I need to go to something like the Orbi system?

Also, I would like to get good coverage in my garage so I want to make sure I include that in the thought process.  My ISP is Spectrum at 200 mbps if that matters.  I want to be plug and play and something that I don't have to keep switching from one wifi band to another.  Which is what we have to do now.  IF we go in the Family Room, we switch to the EX8000, if we are on the Main Level, we switch to the R9000.  Anywhere else, we try both to see what works best. 

I had previously used 2 UBNT APs and had good luck getting coverage.  However, they were VERY old and once I had a problem I realized my technical skills were not up to par and I couldn't/don't have the time to spend trying to get them to work. I am half tempted to get their updated AP, but scared of it being too complicated to maintain.

If I need to supply more info, please let me konw.  I appreciate anything someone can do to help me here.

THanks..