This isn't a popular opinion, but I think window units rock.
Don't get me wrong, I own and run a central air system. And it's expensive to run. And very expensive to replace. Expensive enough that I ended up doing it myself, and becoming trained at the community college to run a business doing it as a mechanical contractor for others.
Like 5-10k expensive to replace. I do it independently on the side and a decent sized house with a 4 ton will still cost at least $4500. And that's from the guy who isn't paying his mortgage and feeding his family doing it. That's over $1k/ton from mr. independent contractor. A ton is 12,000 btu.
A 12,000 btu window unit from Home Depot? $349 + tax. Makes you think...
I'm pretty much right there with you. I dread replacing my heat pump system. That's going to be spendy. I'd use window shakers if I could, but my HOA won't allow them. And, to be honest, I really don't need them since I increased the insulation in my attic a few years ago. I set the AC to 80 when I get up in the morning (72-74 at night), and even on blistering hot days when I get home about 12 hours later will often have risen only to 76 or 77.
I grew up in a Victorian with no central air, and just a couple of window shakers. Uncomfortable at times, but hey, I was a kid.
Mom now lives in another Victorian, again without central air. She can tolerate the heat a lot better, but I still have window shakers in her bedroom, her office, the kitchen, and a BIG 20K BTU unit, I think, in the living room. That one gets used mainly when I'm up there because I simply can't tolerate the heat. The blinds on the porch also help by keeping the sun from beating into the living room in the afternoon.
Speaking of which, I need to buy new blinds for the porch....