Think you have it pretty much summed up - you save 10%. Not terrifically large amount, but pretty good considering how much all of our family vacations cost.
We used almost all of our $961 rewards cards last trip to pay for food & merchandise, so it ain’t hard to spend that money. 
Don’t see me getting that many Disney Rewards all at once for awhile, so I’m considering trying this Target technique when I do have a definite trip planned. (I’m actually mulling over a Super Cheap AP Technique using rewards this year, if I can sell my wife on another trip. Well, actually she is sold already, but a new kitchen counter top and oven are higher on her list than Disney right now. Go figure.)
One other thing: I just replied to one of the chat threads where QueenElinor was thinking if she used her Discover card, which has 5% cash back to buy the Target gift cards she’d be getting 15% savings - she’s thinking of getting an AP, and that would likely return better savings than the current bridging savings. Seems legit after I thumbnailed a spreadsheet on it, assuming she can buy more than the $300 Target gift cards per household the Target policy states.
