I've had the exact same problem here, and I've also drilled holes in the sides of containers to hold water. Depending on the heat, water quality and what's in the bottom of the container, things can get funky down there. I ended up going with big saucers, because I can tell how fast the plant is taking up water.
Another trick I've used is to cut water bottles to make 3" tall "cups" and set them in the bottom of containers with normal drainage holes.
It's hard to find real soap anymore, and the detergents in most cleansers are probably harmful to the soil, plants and soil organisms.
The alcohol-based surfactants are the most powerful, but are probably not that good for soil health, so I use CoCo-Wet and other horticultural wetting agents, one of which was a Yucca-based wetting agent that I can't remember the name of. They work fine, but I've heard that regular use of any wetting agent isn't recommended–the person said something about soil structure and water-uptake chemistry. Seems to me that daylilies get so much water run through them that a dose of wetting agent once a month shouldn't hurt anything.
I think the soil "shrinks" initially because of root contraction, and once a channel for water appears, soil can escape from the pot, the rootball dries more, and a viscious cycle begins.
Capping the soil mix with a thin layer of garden soil has worked very well for me, because mineral-based soil re-wets easily, resists channeling, and promotes slow, even percolation. It also works its way into the potting mix slowly, which seems to help all aspects of plant growth.
In extreme cases of dry rootball, I have to dunk the pot in a big bucket of water for a couple of hours to soak it all the way through. That's when the wetting agent really comes in handy. A good rinse-through afterward, and some liquid fertilizer, and they're good-to-go again.
Recently, I've had good luck using a bark-heavy mix. It seems to stay broken up better than bagged peat-based potting soils. Fine orchid bark, with particles around 3/16 - 1/4 works the best.
A good starting point is 5 parts bark, 1-2 parts potting mix, 1part perlite, plus some dolomitic lime. There's a lot of info about this mix online, search "5-1-1", "container" and "soil".
