Given that line arrays have more focused vertical dispersion (less floor and ceiling reflection), and that line arrays only lose 3dB SPL for each doubling of distance (vs. 6dB for point source), they're probably a good candidate for your enormous listening area.
What are the advantages of a line array design?
.
What are the advantages and disadvantages of a line array speaker design?
.
What are the advantages and disadvantages of a line array speaker design?
.