You need a tighter option between less than 500 and more than 1000.
Until 2006, my parents lived about 200 miles away, but in 2006 my dad's company transferred him to Mobile, so now they're about 1000 miles away. At 58, they're hardly in their twilight years and my brother is nearby, but the hope is they'll move closer after retirement. That's a possibility since our entire family is here on the East Coast.
My grandparents (dad's dad and mom's mom) are the bigger issue since they're in their late 70s, but they're only 5hrs from here and both have a child and other relatives living near enough to help if needed. Also, since they didn't live like hermits, they have friends and neighbors who they are friendly with and can receive help from if necessary (and provide help to when needed as well).
Chris