I would recommend one of the mesh products. I bought the Orbi but there are others. You need to see how many devices you need to figure out how much it will cost. The xFi pods come in packs of three and I probably would have had to buy six to cover my home. I bought one Orbi and two satellites.
Be sure to watch some youtube installations for each product to see what you feel good with. There can be some tricky installation issues.
Do a google on mesh and tri-band.