The few times I have reserved more than one room, the hotel has been gracious enough to allow breakfast for both rooms. The latest was both the Crystal City and Crystal Gateway Marriotts in DC. They didn't have any issues with giving CL access to everyone in both rooms and the Gateway provided breakfast coupons for everyone on the weekends. (We were traveling with friends.)

I suspect that per the rules, only the room with the elite member has to be provided the elite benefits. But my experience has been that the majority of the hotels tend to provide it to all the rooms.

Now your second issue of them telling you one thing and then changing it after you had got your food was a little lame. Even if they changed their minds, I would have expected them to say, today we will honor what we told you, but starting tomorrow no free breakfast for the other room. Personally, I think you handled the situation pretty well by saying you weren't going to eat after all then. If they can change their minds, why can't you? So good for you on doing so. ^