Carrie - had to reply as your DD sounds just like mine. Hours spent poring over t'interweb pulling up pics of cute pups.
It was when I found her google search entry: 'how to persuade your mum to let you have a dog' that I realised things were getting desperate and this wasn't just a passing phase.
However I was absolutely military in planning this whole dog thing. I knew I was the one who was going to be left picking up the poo, basically, so no matter how cute the miniature daschunds or the tea-cup yorkies she had fallen in love with, I had to be sure the dog we had was going to be right for me.
After a LOT of research I decided a whippet would best fit with our lifestyle - happy with a mad walk, but also a couch potato, not yappy, nice size (not too small to be stepped on by kids, not too big and bouncy), non sheddy.... etc.
I went for a puppy so I could be absolutely sure of background and found a local woman who had both mum and dad dogs and just had one litter.
I took DD to see the pups when they were about 4 weeks old. I told her we were going to visit a friend of mine. She had no idea what was going on. We got to the house and there was a photo of a puppy on the door and DD said 'ooh, puppies.' The lady answered the door and asked DD if she would like to see the puppies. Of course she said yes please. So we went into the kitchen and there was a basket of little pups and one of them came right and snuffled his way up to DD and the lady said:
"And this one's yours."
Well. You can imagine.
Not a dry eye in the house.
Three years later and that pup is now a dog, snoozing on the sofa, waiting for DD (his best friend) to come home.
My point is that if your DD is absolutely dead set on a puppy, don't be swayed by pics of cute fluffy bundles.
Really think about the dog that would be right for YOUR family because a puppy is blimmin' hard work and if you haven't chosen the right breed with all that you expect from that, it is going to be even harder. And your DD will love it whatever it looks like because it will be your very own.