With the assumption that everyone in my family has a smartphone of some kind, the question becomes whether members of my family should buy a laptop or a tablet as their primary computing device while at home. I think my general answer is choose one or the other depending on whether you need a keyboard regularly, but you will only want either a laptop or tablet and not both.
I did a blog post once about why I thought the tablet craze has died down. I basically said that the differentiator between a tablet and a small laptop like a Chromebook was the lack of a keyboard. If you type a lot then the lack of a keyboard on a laptop can be a hindrance. While you can get keyboards for tablets, they typically are structured such that you must have a flat surface to place the tablet and keyboard on, unlike a laptop which will work as-is in your lap.
I have continued to agree with this assessment. The point of this blog post, though, is to say a good-sized tablet -- that will depend on you, so try to play with various tablet sizes to see which ones seem reasonable -- can replace a laptop if you don't need a keyboard regularly. If you write emails on a regular basis, then get a laptop. But if you can live without a keyboard and you still have access to a laptop for those times when you need one then a tablet can work. It's worked for my father-in-law quite well and I don't see why it couldn't work for other family members. And if you so choose to buy a tablet, the recommendations I made in my mobile phone post hold for which tablet to buy.