My first thought when I read this question is "When is the birthday?" If it is soon then I would be concerned about the weather. If it is cold then nothing you are planning will work...if it is warm then I say go out front and invite some neighbors too.
The next 10 days are going to be in the 60's and 70's in the middle of the United States. Who knows what they will be later on. We could have sleet or a blizzard...LOL.
I think having the bounce house is a fun idea and the idea about putting up sheets is good too. You could always use streamers from sealing to floor and you could add stuff to them like gems or glitter to dress it up.
Hope it works out weather-wise for you and that your girls day is extra special.