Well keep in mind I have 3 little boys who play with this stuff!
So that's why the 3666 is a must - because without a lot of supervision they knock that one down as well yet it holds marvelously compared to the rock castle which seriously didn't last an hour with the same amount of play that would have taken down the 3666 castle in a couple of weeks!
Last night I got each of my boys the new build-your-own klicky mystery bags. That turned out to be a HUGE hit with my boys! One of them carried his knight around with him all night long as we hung out downtown and danced around with live bands in the street, etc. Then he slept with it! He thinks of himself as very smart for being able to put him together in a matter of seconds - I love how PM's offered this option to kids who might like a little ego boost - haha.
Enjoy your new sets and let us know how you like them!
Well,
yes, I have the Rock Castle along with the extensions. It looks stable enough but I doubt if I can hold it form one tower 
I'm about to order both 4865 and 4866 soon... Can't wait to complete the new knights collection
