What would YOU have done?

Super long trip to Tar-jay this morning (thank goodness we were overcharged (9 times) for two items so the total actually was less than the $888 that I was charged...now just need to go back). The plan had been Tar-jay, then supermarket, then Sabrina could have cookies. Well, after we took so long at Target, even I needed a treat. And Sabrina had been GREAT. A few cases of the "gimmes," and some trouble when I tried to get her to choose between two hoodies--one was pink and purple, the other Hello Kitty--a tough choice--but she was overall really good. She also had asked for chocolate donuts when we happened to be in that aisle of the store, but they didn't have the ones that I like.

So we took all of our goodies to the car and I asked Sabrina if she wanted to get a chocolate donut because I was so proud of how well-behaved and patient she had been in the store. (The problem of this particular Target is the Dunkin Donuts in the parking lot...though if it hadn't been there on Friday, I would have gone from breakfast to 9:45 pm without any caloric intake.) We got in the car and she started asking for cookies. I told her she had to choose between cookies and a donut. She chose donut but then asked if she could have ONE cookie. (We have those 100-calorie packs of teeny tiny cookies.) I said yes, she said "five?", I said no, and I handed her one cookie. She threw a fit that I hadn't let her take the cookie herself.

We went towards Dunkin Donuts anyway because I had told her she could have the donut and because the tantrum over the cookie wasn't related to the good behavior she was being rewarded for. (As an aside, I should say that I wouldn't have used a donut as a reward if I hadn't wanted to get a super-sweet coffee from there myself.) But when we parked there, she wouldn't let me unbuckle her seat belt, wouldn't unbuckle it herself, was hitting me, and other unpleasantness. When she hit me, I closed her door, got back in the drivers seat, and told her that we were going to have to go home. She then screamed and cried most of the way home, including a not-so-adorable (but made me laugh) hand in my face with Sabrina saying "blah blah blah blah Talk to the hand cuz it don't understand." I listened to the radio and didn't engage her, especially because she told me to be quiet when I tried to.

Is that what you would have done? How could I have handled the situation differently? (Specifically the at-dunkin-donuts piece, but also the drive home.)