Here is what I have so far. I'm planning to use a different background for each row. So here is the last row. For some reason I decided to start at the caboose rather than the engine. LOL

I like the landscape best, but believe you could work both in. Like your idea; good luck!
Mariah.

It would look nice with the landscape fabric.

Both.

i like the landscape it looks like the train is in the country

This is so cute that whatever background you decide on will be terrific! Be sure to post a picture when you're all done.

It would look great if you used both in the same block. stack the two backgrounds (alternating them) and then cut a gentle curve through them so that you have a skyline -rolling hills affect (just make sure your cuts start and stop at the same level so they line up later-side to side). If you cut them all together and then bring half of the back one to the top of the stack you would have cuts that line up to sew. Would have to allow for the seam when doing this.

Or keep them the way you them layed out but cut a soft rolling cut across the top of the row and then a row of the sky as a straight row of sashing between the train rows.

I would probably use the landscape and put a border of the sky on the top at least.

I like both, with smaller emphasize on landscape.

Sky. I'd use landscape for the backing
RST

Incorporate both.

How about piecing the landscape to the sky and using both?

Sky

I would use sky as the train compared to the landscape is huge!

I like the landscape.

Landscape. IMHO

I would use both.

Landscape or both.

very cute.

wht not alternate them ?

I would go to the drapery fabric section of your favorite fabric store and pick out a light weight fabric printed with landscape and sky, possibly a western design, use full length of width as much as possible and incorporate the train blocks with the design. There are ways to make this look unique. Example:
Make your train blocks separate from the background, edge with prairie points and applique to background in a pleasing arrangement or make very large blocks to compliment the train blocks.

Take a look at the soldier quilt comments. There is one with a pheasant in the middle. Perhaps a design similar to that would work.

Check out the quilting book Hobo Quilts - not really sure about the name. There is a cute pattern of trains and also all the details of the "Hobo's" language they used.

landscape

I would use both.

I think both will work.

The sky offers more contrast and the train pops out better, in my opinion. Great idea.

Landscape looks great. Just my 2 cents!
Blessings,
MaryAnna

both

I agree

Landscapes - plural. The print you have is great, then have the train go through a desert, or snowy mountains, whatever.