While not an Easter basket hunt, we hid 4-6 dozen regular plastic eggs and 2 dozen of the larger eggs outside at my parents house one time, for all their grandkids (2 under 5 and 8 pre- or early teens). The smaller eggs were filled with Easter candies that they all would like and the larger ones were filled with other goodies an older kid might enjoy (a few had a scratch-off lottery ticket, some had $1 or $5 bills, gift certificates for a variety of fast food chains, off-brand Hot Wheels-type toys, bouncy balls, etc.). My 3 sisters and I coordinated and agreed on how much we'd each spend, who bought what, who had plastic eggs they could bring from home, and we all filled them once we got to my parents (my DMom conveniently "forgot something" wink-wink for dinner and sent us girls to the "store" (their garage, where the brown-n-serve rolls were sitting in a bag on a lawn chair), where we filled and hid everything.) At that time in our lives, we did not live near each other (Chicago, Detroit, Grand Rapids, and SW Michigan; parents were near Kalamazoo), or we would have gathered at home to fill the eggs ahead of time.
We set a number of eggs for each size (maybe 8 small eggs and 3 large eggs each?), so everyone cold have an equal amount of eggs. It was what was in them that was the surprise. The "littles" wanted to immediately open every egg they found, where the older kids were all over the yard, getting everything they could and, surprisingly, when they got their "share" they started helping the little ones find hidden eggs. Once we thought everyone was done, the kids each got a bag for their haul and we counted up the eggs. We told the kids how many were still missing and everyone was off on the hunt once again.
It was the last Easter we celebrated at my parents home and it is a memory we all treasure.