My girls and I just started caching. We've done 2 caches so far and had a blast. I must say I was disappointed, however, at the poor condition of the contents (which is why I went looking for this thread).
We've already started a "booty box" to collect some really cool and interesting stuff to leave in future caches. So far we have a bronze Mt. Rushmore bell, a plaster statue of Crazy Horse Mountain, a set of cool slot machine dice, and a stack of zip-locked paperback books (which I need to log into bookcrossing). Collecting the booty to leave or trade has been fun for them, too. And we've already talked about "clearing the cache trash" on our future finds.
I agree, the hunt is fun, but it's also delightful to find a real treasure. On our first 2 caches we took my cousins kids with us and the kids ended up trading amongst themselves things we'd brought!