Me again ...  

I was thinking more about the sending addresses in the address book and I identified two use-cases that need a different handling:

A.) In my address book I want to have addresses of my other wallets, of my girlfriend, my children, etc. I can send coins to them repeatedly and I see whom I've sent coins to in the transaction list.

B.) I'm buying something with my coins. I'm getting an address for this transaction. I will never need it again -> it shouldn't show up in the address book. But still, I want to see in the transaction list, what I spent those coins for!

This could be implemented using the same "hidden" flag as proposed for the receiving addresses.

I'm curious to read your comments.