The things mine like to play with best are their wheels of course, their sandbaths (just a plastic tub with chinchilla sand), toilet roll tubes, they each have a couple of little houses they like to hide in which are good. They all like to chew off and hide their millet sprays..don't think they ever eat any though. Those puzzle playgrounds are meant to be good and are on my list to buy. They are plastic though but that can be good too as they are easy to wash and dry. Oh and Mavis spends ages chewing her vitamin block to sand which is has to better than chewing the inside of her Imac Fantasy.
I got a couple of things today that they haven't played with yet. One of those wooden shapes on chains, garland thingys for each of my girls and a nut knot nibbler for my little boy. I'll let you know if they show any interest in those.
I will watch with interest for anything I haven't got yet!!