Car.
Shuttles are unreliable at offsite properties.
You get used to the Disney busses running every 10 minutes, and expect that kind of service. You'll be let down when a bus doesn't show up for 30 minutes and the hotel doesn't care.
And you know what, they're starting to charge a fee. I took this picture of the shuttle times at the Amerisuites, which is located across from the USF parking garage. Look in the top right corner, it says $9 pp/rt.
http://www.nogodforme.com/images/DSC05884.JPG
I realize that paying $9 per day, for 3 days adds up to $27. Here's an idea you could do if you want to save the money. You could try it one day and see how it works. Look at my web page for free parking here.
http://www.nogodforme.com/offsite.htm
Have the husband drop you and the kids off at the drop off of the parking garage. You don't go into the main parking area, you go into a different entrance that say Busses, and drop off.
Then the husband can go park the car in the TGIF lot, walk, and meet you in the big circle where the garages connect. The first pictures of this page show where you could meet. The dropoff has stairs that lead to the big circle area.
http://www.nogodforme.com/arriveearly.htm
Maybe you could pay the first day until you see what I'm talking about, then you can park across from the garage.