I think they're bored also, but more toys might not be the fix to the solution. Mine have tons of toys in their play area they stay in when I'm not home, but I still find chewed blankies or shredded toys because they get bored and have too much energy.
I think taking them for a walk before they go into their room (or adding length to your current walk) would let them release energy before they are in their room for the day. A tired dog is a happy dog
