It's according to what you want to do with your laptop. I use mine to ONLY surf the web, read and respond to email, forums, Facebook, etc. I also use it to write papers, letters, etc., but don't really need the complete functionality of a laptop.
I'm not in my 80s, but in my 60s and I purchased an 11-inch Chromebook for less than $150 at Walmart and I LOVE it.
If I need to take notes at a meeting at church, I will unplug it and head to my meeting. It has a long battery life, I have WordPerfect installed so that gives me use of Excel, PowerPoint and the other products of Office 365.
My daughters have 17" laptops and husband has a 14" laptop. The keyboards are the same size other than the number pad on the right and mine has the number ROW on top as well as the F-keys on it. Mine is an HP Chromebook.
Hope this helps.