I know I'm late to the party here but what about retired military working dogs? The husband and I had planned to go that direction but we had a 12 lb little alpha boy to worry about so we went with a puppy. Our next GSD will be a retired MWD though and many of them are ready for a slower pace so do not need all the exercise of younger dogs of any breed and they are very well trained well before you get them.
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Live every day like he deploys tomorrow

Proud parent of two furkids:
Dexter - Schnoodle - born 05/02/2009
Neeko - GSD - born 11/16/2012