Maybe you should let it go for peace's sake, but I'm always appalled at the temperatures you guys throw around.
I live in what is officially subtropical climate (a few miles south of the tropic), and we get "winters" with temps as low as 41 (usually at night time, but every few years we get a 41 during the day with a 34 at night). Summers go as high as 97, with again the once in a while 100-102. Now here's the shocker:
Most of our houses don't have heating/cooling. Plus we're pretty bad at building for cold weather specifically.
I've never had AC in my house (except for a single unit at my parent's office when they started working from home), and never had any central heating. What we do is use portable fans for when it's too hot (in addition to wearing just shorts and tank tops inside the house, but I've been known to waltz around in a bikini on extreme heat), or small heaters for when it's too cold (in addition to at least one sweater, but when it gets to 45 outside, and you're like 55 inside, you might want to put on some extra clothing). This way each one handles their own temperature, plus you practice your temp tolerance and grow your badassity muscle over the years.
68 is too damn hot for winters. People in Rio de Janeiro put their ACs at 62 in summer. I'm cold sensitive, but I can still deal with 62 just fine, wearing a very light sweater. I would say if you want to be mustachian, keep it at 60. For my SO, this means only wearing pants and a sweater. For me, sometimes it'll mean wearing something a little warmer, like the summer sweater I bought in Toronto. I'm sure someone who bikes in winter can weather that just fine. My finnish friend says he wears a tshirt with temps as low as 50 inside the house.
That said, 68 is too damn cold for summers. That's the temp I use in the car for 2 minutes when I want to cool it down quickly. The regular would be 75-79, but I even think that's still very comfortable. I'm probably sitting under 86 degrees with a fan while my SO does his routine workout. Yesterday we went to sleep and it was around 93 inside the house. I took a 30 second cold shower just to get a little wet and air dried (naturally). Comfy for bed after that! This isn't really "oh I love this temperature" comfortable, but honestly it's pretty okay and why would you waste resources and badassity potential on AC?
I congratulate everyone who can go even one degree further on their comfort zone, but I still think you-all could do better... All that AC and heating has made your frugality muscles very flabby! :)