I would enlarge the pattern first and then make the buildings taller, by adding some blocks at the bottom. Then you could add a base on it like a street or something like that and then finish the size with borders all around.

Since you have a pattern and it appears to be square and triangles...I would draft it on graft paper and just add rows to make it the size needed

Maybe if you made everything twice as large as the pattern calls for. You may need to add other rows to make it wide enough. Then, because the rectangle goes the wrong way for a bed, add the background fabric to the top until it is long enough to cover the bed.

Use as the centre piece. The outside could be sky lines of different cities in black on a coloured back ground.

Thanks so much for the suggestions. I'm still not exactly sure what I am going to do, but you have given me some great ideas.

I think if I were adding borders to make it larger, I would use a solid (or print), then a pieced in the tower colors, and another solid to let the center panel be the starof the quilt