Margaret...we really had good luck with hummingbirds once we started having a colorful flower garden easily seen from the air, but it sounds like you've already tried that. One particular plant my hummers go gaga over is called Black and Blue Salvia (Salvia guaranitica). The flowers seem to bring them in and the feeder gives them a bonus. They carry this plant at all our local nurseries, though it comes in later than our usual spring annuals (here we start seeing it in the garden shops about May 12th or so, when most Kentuckians have already done their spring planting by the first weekend of May).
Word from the experts is that plain sugar water is healthier...or at least it works just as well and the scientists just aren't sure that the red food coloring is harmless.
We use this HummZinger feeder:
http://www.hummzinger.com/mini.htmIt's extremely easy to keep clean; I keep two of them that I rotate daily...I bring one in from outside that goes in the dishwasher and hang the new one. It's been really hot here, and my feeder's in the sun, so I really have to change the nectar every day during the summer. I mix up about a 10-day supply of sugar water, keep it in the fridge, and pour about 4 ounces or so into the fresh, clean feeder every night.
I've attached a photo of one of my birds on the Salvia Guaranitica: