How should I replace a 1950s sliding patio door??

[Anna Watkins]

I have a 1957 3 BR/1.5 bath ranch house in the Belvedere neighborhood of Decatur / Atlanta, GA.  The original sliding door going out to the deck may be beyond repair, and I'm looking for ideas on how best to spend $$ to replace it.  The rough opening is approximately 80" x 144" (not quite as tall as modern doors).

Who's had to do this?  The house is currently a rental (let's say B-ish class) but the 10-year-ish exist strategy might be to fix and flip retail, depending on how the market is when I'm ready.  Do I put money into whatever the end product might be (french doors or a window/hinged door combination), or just do a straight modern-quality replacement for now?  We're talking $2,500-$3,500 for a straight replacement.  

Is there a cheaper and still decent option, besides just bricking it all in?  All creative ideas welcome!