I'm like Goldilocks, in that I tried one loft too big and one loft too small before building one I think "just right," an elevated walk-in with a 4'x6' footprint:
As you can see, it's well ventilated, both for the birds' sake during our summers and to limit the amount of "dust" I'm exposed to while in it. And the size allows the birds room to move out of my way when I enter (instead of out the door) without getting far enough that I can't easily catch whichever one's I want without having to chase them around. Everything except the nest dividers is treated or roofing metal that can be hosed down for easy cleaning without a lot of scraping, but since the floor is grated, most waste goes out the bottom and only needs shoveled out twice a year.
I've double nest boxes for six pairs, so they can lay a second clutch of eggs while still feeding earlier young that aren't quite ready for the floor. (The less fighting there is over nest space, the more fliers are produced.) Nests need cleaned out after every second or third clutch, and I facilitate that with separate hinged, drop-down fronts on the nests that let me clean one without disturbing nesting in the other "duplex" half. Also line the bottom of cleaned nests with a double layer of wax paper topped with a large paper plate, which lets me easily pull out the whole pine needle "re-bar" and pigeon poop cement lump at once and avoid most scraping. I provide pine needles in a bin from which nesting birds draw as needed:
Pigeons will eat most anything, and plain old "all stock" feed pellets are probably as cheap and easy as anything and require no additional grit, but pelletized feeds produce looser, smellier, more cement-like stools than grains do. Grain stools have little odor and reduce scraping at clean-up time. And the birds much prefer grains - except milo, which they seem to know is about as nutritious as styrofoam. I feed mine whole waste rice, which is free in the field or from farmer friends, but dryers will sell you broken and other waste rice, like sweepings, dirt cheap. Pigeons also love whole
corn and do well on it, but be aware that sharp cracked corn edges can be bad news for tender baby pigeon crops. One rub with grains is that the birds need grit to help process it, which you can get them at a feed store, or they'll find on their own if given free time out of the loft. The other grain "rub" is that I've found I can up baby production by supplementing it with 17% protein "laying pellets," not that they won't lay without it, just that it puts them in over-drive. (Commercial "pigeon pellets" are also 17% but a little more expensive.) I keep laying pellets available in a "bullet domed" self-feeder, and the hens pretty much use them as needed, while still preferring their rice. Also like the bullet self feeders for water, as the birds can't foul it. Have built a PVC pipe waterer with bump nipples that worked fine and held a whole lot more water, but found I'm more apt to remember to check the translucent bullet waterers that need only a glance.
As for the pigeons, themselves, feral pigeon will home to the place they're first flown, just like homers, per se, but my experience has been that only racing homers can be counted on to home long distances. My common birds were reliable at seven or eight miles and lost at 20. If you start with adults with strong homing instincts, you'll have to let them raise a brood or two in their new loft before freeing them, so it's quickest to begin with young "squealers" or "floor birds" that haven't flown from any other place yet. Those you can safely release after a week or two in their new home.
And if you decide to fool with it, there are "tricks" to starting your birds homing and to keeping them from being a pain to neighbors or hawk bait that we can talk about as that time nears.
Fwiw, aside from semi-annual clean-up and times when I want to mess with them, I doubt I spend more than a couple minutes a day on them. But it sure is nice to have them when I want them, and we enjoy watching their exercise flights. In fact, the only complaint we've had from neighbors is that their evening exercise flights are suspended while I'm at the lodge during hunting season.
If you think I'm wrong, you might be right.