a few amigos and i have this thing we call an egg route in each region--mainly for shiny pokemon things
in kanto, it starts in celadon, goes through cycling road, enters fuchsia, circles back up to lavender, and then taking the underground tunnel/going through saffron to get back to celadon
occasionally, though, i just stay on four island to get the eggs when they become available--as i generally do with each game
in johto, it starts in violet, goes down to azalea, over to goldenrod (making sure to pass by the day care to get eggs), and then through where sudowoodo was and then back to violet
hoenn is actually just a line for us
from mauville to verdanturf and then back, going a little bit to the right of mauville as well
it's literally just a straight shot and includes the day care to get eggs again
sinnoh starts in eterna, goes through mt. coronet to celestic town, goes down to solaceon (making sure to pick up eggs), and then sweeps down to hearthome. it then goes back through mt. coronet and then up through cycling road to get back to eterna
unova starts from nuvema, up to striaton, picks up the egg in the day care, over to nacrene, over skyarrow bridge and into castelia. after getting give eggs we go up to the diamond shape route around the region (nimbasa, driftveil, mistralton, icirrus, opelucid, lacunosa, undella, and then to the game-specific city place thing)
kalos goes around the figure-8 loop thing that is the majority of the region, picking up the egg at the day care along the way
some modifications have been made to each of these to better fit various cycles