If it was me (well it was) I scanned all the letters (took forever) and had them made into a book, just on one of those online photo sites. Which had the advantage of also being able to include pages of notes and photographs relevant to the content of the letters. Had several copies printed for family and then I sent the originals to our national archives (who fortunately wanted them) If they hadn't I was preparing to buy proper archival boxes, which seem to cost an arm and leg, to store them in, thinking that they didn't need to be handled at all since anyone who wanted to could read them in the books.
