The hummers are probably perching in the trees for protection and to watch over their territory if they are not migrating through. They are pretty efficient and quick when drinking nectar from plant blooms. They are hard to catch sightings of at the flowers unless you are sitting out there waiting for them. At feeders, mine perch on the feeder perches and drinking for a while. But at flowers, they are quick.
The trick with sugar water feeders is to keep the water changed every two days in the summer so that it is always fresh. If mold develops in the sugar water, the birds won't come back to that feeder. Some folks use a higher sugar content like 3:1 (3 water to 1 white sugar (table sugar)). Yellow jackets and bees are a real problem with some types of feeders. Maybe your neighbor was whooing them away from your feeder by doing those things. I think your decision not to offer a feeder was smart ... if you don't have the time to mess with a feeder, plants are always much easier and better for these little birds!
