My simple thoughts, some of which have already been covered:
Toilets, the last one I installed in our house was called "smart height" or something like that so it sounded better than ADA. Best investment ever, it is a THRONE! Every time I go to someone's house now I think to myself: "What do only two foot tall children live here?"
Attached garage or a breeze way, in the north heated. I have lived in both types and I'm sorry but it sucks walking through weather to get to your garage.
Outlets, in my last house when I finished the the garage I put two outlets every four feet. Overkill probably but although time consuming I hardly ever had to run an extension cord. And the cost was minimal. I miss that garage. Now I have to hunt for one of four or five outlets.
Shower and toilet in garage. Period. Preferably some form of stainless steel insert if they make such a thing that you can pressure wash (hey we're dreaming right?). Spouses do not like your greasy handprints. Nor do I like cleaning them up after a long day.
Agree on everything said about ADA. That time is not too far off in the future at my age. Get it done now.