First off, you want to build this document as facing 8.5 x 11 pages, not as 17 x 11. You are making an incredible amount of extra work for yourself. There is no way, short of cut and paste, to rearrange your half-page panels into the proper order for printing if you've been working in consecutive order.
By doing the letter-size facing pages you are able to do your layout in "reader spread" order, or the way the reader will see the pages when the document is finished. It can then be "imposed" (re-arranged into the correct order for printing) into "printer spreads" using any of several techniques. Keep in mind that if this is a two-up folded journal, as you describe, you must work in multiples of 4 pages.
Page imposition is really the job of the printer. You should not be doing this unless specifically instructed to do so. The printer is in a position to know how he will be arranging the work to fit his equipment (and that will depend on the type and size of machine that will be used for output) and you are not. In order for him to do the imposition he must have your document set up as individual letter-sized pages.
If for some reason you really are supposed to do his work for him, you can impose using either Print Booklet from the File menu, or an imposition script, of which there are several available. Using print booklet you must print to PDF, which requires that you have a PDF virtual printer. If you have a full version of Acrobat, the PDF printer should be installed by default. If you don't have a PDF printer you must use one of the scripts to shuffle the pages (or do it by hand which is tedious and prone to errors), then export to PDF, being sure the "Spreads" checkbox is checked.
When you are done with either of these imposition methods you will have a PDF with 17 x 11 pages, each with a pair of your 8.5 x 11 pages on it.
Peter