First, furniture.
The Balloon Chair at Horchow.
Gondola Day Bed. This is one of my all time favorite pieces.
"Basket" like Cocktail Table.
Lights
These lights at Pottery Barn look like something you'd use in WWI to spotlight airships in the sky, don't they?
They come in a variety of sizes and shapes -- tabletop, spot, and task.
Walls
This is the hard part. I'd consider this Balloon WallPaper.
But it might be a bit kitschy. Perhaps some seagrass wallpaper wainscoting, to evoke the gondola of a small balloon, and then perhaps paint the walls sky blue (with clouds?) above the chair rail.
Don't forget airship posters.
Finishing Touches
I like the idea of a compass on the floor.
These playing cards on the table.
And a stormglass hanging on the wall.
There. Now that I've gotten that out of my system I can return to daydreaming around rooms I actually have.