I love rats. We where going to get some awhile ago but we saw some degus and fell in love. The degus are great but you really cant handle them like you can with rats.
Regarding boredom breakers. Pringles tubes are great. They are big enough that rats can get through them without getting stuck and they are also safe to be chewed on. You can string them between ledges as well to give them tunnels to run through.
Lava ledges are good too as it gives them something to climb on (and helps keep their claws worn down) and also gives them something to gnaw on to wear down their teeth.
Not sure if rats would like it but we also sometimes put a container of compost in the cage or play area of our degus with some nuts buried in it. They love digging around in it but it does get messy