Playmobils are a great investment. Our son turned 5 yesterday and got the big Jet Airplane for a present. His 8 y.o. sister is as excited as he is. All of their playmobil people are taking trips around the house. We have a large bin of playmobils passed down from their college age brother that get lots of regular play.
Our children play differently with them depending on their current age. IMO, age 4 is about the earliest that they really started to enjoy them. I especially like that they never need batteries or make obnoxious sounds.
Last Christmas they received a box of building blocks (just plain wooden blocks - the kind you would see in a nursery school). They almost always get the block out to build new houses/roads/etc for their playmobil people.
Playmobils will be one of the few toys I box up and hang onto when they finally outgrow them.