We have them all year,but the bees start coming this time of year and can be a pain for us and the humming birds.Our most popular feeders are next to flowers.
Get a flat feeder, like a Humzinger. Bees, wasps etc can't reach the sugar water so they don't bother it. Also much easier to clean and therefore safer for the hummers.
The Anna's are quieter at my house in L.A. because the Allen's drowns then out--tiny but might territorial ones. I have 2 that live in my yard most of the day and the Anna's only get a sip when the Allen's are away. They both make a chip-chip sound but Allen's goes on and on. I wouldn't describe Costas as a giggle. It's a whistle that rises in pitch. I had one in my yard for years once and I haven't forgotten that distinctive sound. I think the Calliope might be describes as a giggle. Check out hummingbird sounds on the All About Birds site
