Almost my whole house is CFLs, the only exception being two rooms (my office and the living room overheads) that have dimmers as well as some desk lamps, etc. I don't have a problem with the lack of instant-on... in fact, in the dark, I almost prefer the fact that they come on instantly to see where I'm walking...but at maybe 40~50% brightness... and go to full brightness within a minute to let my eyes adjust a bit. I don't know what the difference was in the electric bill, because quite frankly a much larger part of the bill is all the equipment that's on all day. Even our front porch lights (6 bulbs on wall sconces and three floods) as well as the floods on our sign out front are all fluorescent. Those, in the winter, might take a full five minutes to get up to speed, but they come on at dusk and go off at dawn, so I'm fine with the slower warm-up and I'm sure that they're saving a good amount on the electric bill.
One thing that I've done...and someone please correct me if I'm wrong here... is to pack much higher-output bulbs in the fixtures since going to CFLs. For instance, I might have a ceiling fixture that's rated to take two 60 or two 75-watt bulbs, but I've replaced it with two CFLs that are "100-watt equivalent". My rationale is that they're drawing less juice AND producing less heat than traditional tungsten bulbs...so what's the harm? I certainly appreciate the extra brightness. I have
found that these CFLs don't last more than a couple of years, and I'm not sure if it's because they still don't dissipate the heat in an enclosed ceiling fixture or I just bought a bad brand in bulk when I first switched them all over 3-4 years ago.
I haven't converted anything towards LEDs yet (the bulbs are still too expensive), but I just purchased an under-counter lighting kit
that was dirt-cheap and has fantastic reviews for the kitchen re-do and I bought a single under-counter strip
to use for a rack in my office. This second one was 35% off at a nearby Lowes that's closing, and man, is it bright... almost too much... but will work well for the task light I needed it to be. That kit from Amazon (first link) sure isn't much to look at, and it's not as bright, but it's a really good value. That company ( Inspired LED
) seems to have a very good reputation and great pricing on LED.