Anthony,
your best fotos are slightly off-center and therefore not suitable for a 24"X36" poster size. Although, we might make 20"X30" posters which happens to be the largest standard size I could find pricing for at www.mpix.com (around $25 per poster).
So, referencing my comments and suggestions below the fotos, note that I put small poster, meaning the 20X30 mentioned above. As far as your inquiries into higher resolution files, no problem. We could work something out so you could get them as TIFF files on a CD. The price increase won't be much, just depends on what you want.
Let me know,
Greg