Hi Emily,
there's a nice little family run hotel here in Volmarstein near where Bully and I live (about 15min from Hohensyburg, 5mins from Hagen by car)
Burg Hotel VolmarsteinI stayed there years ago when I first came to Germany and it was really nice,
although I don't know what the prices are like, it's still got a good reputation.
It's perched on a hill overlooking the Ruhr valley beside the ruins of an old castle
(hense the name) The Village is also nice with a couple of restaurants and pubs
and lots of "Fachwerkhäuser"
If you do decide to stay over let us know and we could meet up.
If you are looking for something else I'm sure can dig up some other addresses.
hope this helps
Neil