You know you don't have to kill Harold right? If you talk to a certain grove member they give you the option of making him grow even faster than he is and extending his reach to the whole of capital wasteland! You get some very nice rewards for it too.
Oh yeah, I'll add this to my list of habits as well, even if it is as recent as 10minutes ago via revelation. No longer will I use Tenpenny Tower as my Player Housing. Henceforth, my hose shall be the Sniper Shack on top of the mountain in North-Western Capital Wasteland (The one which has the Victory Rifle in it)! Seriously, it's awesome! It has two pet radroaches in a playpen who respawn if Dogmeat decides they look tasty(seriously), no npc owners, a freakin huge teadybear with a beer in his hand, plenty of lockers, and best of all, the mountain overlooks a camp of Supermutants who, with the help of said Victory Rifle, make brilliant sport shooting, like fish in a barrel. For those who don't know where it is, heres a link from the fallout wiki;
http://fallout.wikia.com/wiki/Sniper_Shack