We moved into this house (built new) in July 2006. By the end of September we'd replaced every light in the place with a CFL, some 45 or so bulbs. The vanity in the guest bath has four globes and the main bath vanity has eight (it originally had eight *100 watt incandescents!). Most ceiling fixtures have two 40W equivalents, there is a 100W equivalent in a torchiere in the living room and one in the attic, and there are a sprinkling of 60W equivalents in various single-bulb fixtures in closets and stuff. We simply bought the equivalent wattage for whatever came out of the socket. There are four CFL spotlights on the corners of the house, 90W equivalent, on X-10 controllers so we can turn them on from the cars.
Out of the whole damned bunch, I've replaced four of the globes used in the bathroom vanities and one 40W in a closet. That's it! Before we finished replacing the incandescents in the house, two ceiling and two closet bulbs and the one in the attic had already blown (one rather spectacularly) in the first month of living here.
Nobody visiting us has ever noticed the fluorescent lighting unless they see the exposed bulb in the torchiere. The light quality is not noticeably different and we think that we're saving about $25-35 a month on the power bill. So figure it took about 8-10 months to offset the initial cost of the bulbs and I haven't had to drag a ladder out in almost three years.
I'm sold. The only incandescent bulbs still in the house are in the fridge and the oven.