I think 1 is a very nice age - they are more confident and mature - have a lot of personality and still very active. 18 months is also nice - they might slow down a bit but are kind of "wise" hamsters
Our first hamster lived to 2 years 8 months and still used his wheel right up to two weeks before he went. He would just stagger out, hop on it, run for 10 seconds and hop off again. I just made sure the entrance to the wheel was right down at substrate level so easy to get in and out. He did have very stiff back legs latterly and that's when he had to have one level - once he tried to climb onto something and didn't quite make it (he looked very surprised). But he still zoomed around on the flat until he was a great age - out of the cage as well. In fact that is often when they do need more out of cage exercise when they're a bit older and less mobile - helps stop them stiffening up.
I like them when they are older - they know you well and are more accepting and less stressed about things and they do give you kind of "grandpa" looks as if to say - stupid person I know best. Nice that he sits more for cuddles.