I've been running around in circles for an hour and I still can't find the Viewing Platform for the final stage of the Come Fly With Me quest. D:

when you see the building for mteh outside see teh scafolding on eather end at top of left one as your facing the building is teh room you have to go thru inside to get to it

pretty much just go back up to where the Ghouls were where you got the quest, and there is a door that says "to the desert" and there it is.

Follow the objective arrow. It leads to a door (that was locked with a key until this point) and it leads outside to the viewing place.

The door to the viewing area is in the research labs where you met Jason Bright. Ignore the scaffolding outside, you have get to it from inside.

Rina is correct. It is where you met the green glowing ghoul "Jason". It over looks the huge dome that is the launch pad.