Gorky park scating rink is truly amazing. We tested it for you?. It is big but also not to big, even for kids and for people not managing the scates well, although it is better you bring your scates because the ones you can rent there are allready over-used. And as always, try to go in the morning on weekends or early evening on Friday. Then there are not that many people. And regarding skates, best to buy your own, there are promotions in Sportmaster or Decathlon. And you will definitely use them in Russia?