If the tank is truly cycled, adding yoyos shouldn't be a prob; they aren't dependent on a mature tank like an oto might be. Live food is always a plus with loaches; a supply of snails will keep em fat n happy, although they do fine on processed fish foods (my guys, yoyos n clowns, lurve algae wafers, frozen bloodworm and shrimp pellets).
What size tank will you have em all in? Keep in mind angels will need around 10g each. Medium sized tetras are good tankmates, but avoid nippy fish like tiger barbs which will likely chew on angelfish fins even in large schools. Also avoid little tetras that can fit in angelfish mouths (neons are one; it can be done by adding the neons first, letting them mature then adding juvenile angels, but there is no guarantee the angels won't eat em - they eat em in the wild). Gouramis, like the colisa variety, can make good tankmates, but keep away from really aggressive fish.
I've angelfish, loaches and a plec in my 55g; they all get along rather well. Sometimes the plec gets cranky when everyone makes a beeline for his algae wafers (the angels also adore them), and the angels will beat on each other from time to time.