My parents have had 3 different swimming pools built. (Kept moving & missing the pool!).
The first one was concrete bottom with fiberglass walls, the second one was the same, and the third one was with a vinyl liner. Although the fiberglass ones were the most attractive, in my opinion, the vinyl pool definitely felt the best to our feet! The concrete-bottom pools can scrape the bottoms of your feet, and cause stone-bruises on your heels too. Also, the vinyl pools have a layer of sand underneath, so the bottom gives slightly if jumping up & down, etc.
The current pool was built ~1993 I think. They had to replace the vinyl liner once, about 2-3 years ago.