I think doggie daycare is a great idea, just make sure you check it out first. Here's why...
We were in Louisville during Thanksgiving and we stopped into Petsmart, one that had a vet, pethotel, and day care. Honestly, I was appalled at the day care. There was one person in there for about 15 dogs; IMO one other person would have been better. Also, they had dogs in the same room ranging from a small min pin and another toy breed that I can't remember to a HUGE great dane puppy, a big setter of some sort, and several other BIG dogs.
They were going potty everywhere and a couple even threw up. I couldn't imagine what would have happened if there had been a fight. And I felt so sorry for one of the toy dogs that probably weighed between 8-10 lbs, but was smaller. She was just pawing her little heart out at the window to get out.
I wanted to go in there and take her home with me so she'd be safe. She was terrified. Also the person in there wasn't interacting with any of the dogs. She was just standing there.
Now, I know not all doggie daycares are like this but I would definitely check them out before I would put Sophie in one.