Okay, so as a V-day present I declined jewelry. There was a time when I was into gemstones, but now I'm into yarn, so that's what I've requested. I can have
any yarn I want in
whatever amount I want.

I am being taken to San Francisco this weekend and will probably buy the yarn at a LYS there. If I don't see anything I really like, I can always come back home and order it, but I wouldn't be surprised to find myself seduced by touching and seeing great yarns in person.
I asked this on another forum and got many great opinions, but I can never have enough. Who knows when such an opportunity will come again? I feel so lucky and I want to make sure I get just the right yarn. I'm strongly inclined towards a merino silk blend, with the wool for elasticity and the silk for sheen. But if you could have any yarn you wanted, what would you get?