Lucky you, staying at the GF! DS turned 9 months during our Disney trip last week.
We brought:
Our stroller (Bob Revolution)
7 diapers per day
wipes
diaper cream
Ergo carrier
clothes (I packed outfits in individual plastic bags. Normally, I don't waste bags like this, but it was much easier than turning the suitcase upside down looking for baby socks. Each bag contained an outfit, spare onesie, 2 pairs of socks, and four diapers. Enough to do a day at the parks.)
baby food- My DS is still breastfed and eats table food, but I'm picky about about his diet so I brought some organic pouches of food and organic puffs
two hats (extra in case one was lost, he's fair skinned and bald

.)
baby sunscreen
swim diaper
infant ibuprofen
earmuffs (in case the fireworks startled him like they do my DD...they didn't)
new toys/books for the plane
disinfectant wipes
straw sippy
I wish I had brought:
outlet covers for the hotel room
something (maybe heavy tape?) to secure the bureau drawers because he wanted to open and close them all the time
disposable changing table covers for the airport and plane
a seat on the plane! It has always been my policy not to fly my children as lap babies. I let DH convince me that it would be okay this one time and I regretted it. DS was restless in our laps and I had trouble getting him to nap.
What we didn't need:
toys (our flight was three hours and he was more entertained by the magazine I brought, a plastic cup the flight attendant brought, and the folks around us than the toys I brought for him. Maybe I'd bring a one board book and a car or something next time, but not nearly what I brought.