I lived in Seattle until last year when we moved here, LOL! I'm in Ohio now. I still miss those lovely mountains and mild climate. My friends here always laugh at me when I say its just too sunny here too. I guess I am a PNW girl at heart.
Well, a couple of interesting things I learned. We were stuck in an apartment for months when we first moved here so to kill time I took all these gardening classes at our local aboretum. I'm still learning! Trust me. But I did learn tons about organic gardening, composting, butterfly gardens, etc. Interestingly they told me its recommended not to have butterfly bushes in the PNW because they are too invasive out there. They will take over your entire yard because the climate makes them super hearty. SO this probably explains why they do that to your hard, Boongirl. Not sure if they will do that in the bay area, but I'd probably trim them back, because its climate is so similar to Seattle. I hadn't heard of these plants until we moved to Ohio.
Yes, they are supposed to be a somewhat invasive plant in Ohio, meaning if you don't trim them back they can reseed and populate new bushes and grow and grow and grow...exponential effect. However, if they are pruned here they are supposed to be quite manageable. Honeysuckle is supposed to be the most invasive plant here or so I am told. They also gave me a list of all the other invasive plants to avoid (like burning bush shrubs). I think the big thing with the invasive plants are they are also not good for native wildlife and wildflowers. They are supposed to be so hearty they are overdone and can rob the area of natural diversity, i.e. not leaving things for other wildlife like deers, squirrel, etc. to eat. So its an environmental thing too. I wish I had more info--but I've misplaced the handouts they gave me. I had no idea either, but it made a lot of sense.
Thanks for the suggestions guys!