Yes, there are plenty of "drop-in" replacements. My personal favorite source is divinelighting.com (talk to Livingston, he was very helpful). While I was shopping around for appliances, I came across multiple mentions that range hood halogen lights get very hot and uncomfortable. I had some other questions regarding hoods, and thankfully the range hood company representative I spoke with was very helpful, including advising me personally to get the LED bulbs, particularly for the heat concerns and much longer lifespan. I'm using these LED's in my new range hood: https://www.divinelighting.com/bulbrite-ledjc12ww-06watt-led-low-voltage-jc-bipin-g4-base-warm-white-bulb-p-22682.html It's an exact replacement for the G4 base halogen bulbs that came with the hood. Took only a couple of minutes to replace all 4 bulbs, the hood has swing-out light covers, very easy. The only comment I can make is that they're a little dimmer than halogens (noticed that when I replaced 1 of 4, it's maybe 10% dimmer), but I have plenty of light in the kitchen, and the hood is on an island, so it's not that major of an issue. And, considering that they're supposed to last 30,000 hours, spending 5 bucks on them is definitely economical. Love the hood, love the new bulbs! LED is definitely the way to go! Here is a link that might be useful: G4 LED bulbs

One thing that might help with high load-related dimming is a multivolt ballast. I am not sure. They operate on voltages between 120 and 277. It has never been clear to me if they adjust to differing voltages in a discrete or continuous fashion and how fast the adjustment is. Maybe someone else will know that detail. On-off is probably killing your tubes On the other hand, good program-start ballasts are recommended for occupancy sensor use. At some point, you begin to measure fluorescent lamp life in "starts" instead of hours. I wish that I could be more certain that the T8 ballasts will eliminate your noise problem completely. All I can say is that I don't hear mine at all. I know, however, that I have some high frequency hearing loss. Any good new electronic ballast operates above 20kHz for efficiency purposes. They are more likely to cause EMF or RFI problems than audible noise. (They need to be designed to avoid frequencies that cause EMF and RFI problems.) If you buy your ballasts locally, you could just change over one of your three and disconnect the other two for sound testing purposes. If it does not work for you, maybe you can get the store to agree, beforehand, to take the ballasts and lamps back. One thing in your favor is that your lumnaire appears to have non-shunted sockets and is wired for rapid-start/program start. There are some wiring diagrams (and other information that might be of interest) in this link: http://www.lighting.philips.com/pwc_li/us_en/connect/advance/assets/1-01_to_1-69_Atlas2012.pdf I like ballasts that will continue to operate the rest of the lamps if one goes out. Not all do that. I bought two boxes of ten (one each 1 or 2-tube and 3 or 4 tube) on ebay for $10 or less/ballast. I have a lot of linear fluorescent that came with my house and garage. Your light quality is likely to be greatly improved with the T8 tubes. I think that high CRI tubes are available in T12 format, they are not as common as for T8. Look for a high-quality lamp. I bought a bunch of GE SPX tubes. (SP are lower CRI). Other manufacturers have other notations. Color is largely a matter of taste. I like a more natural, daylight color. If you ballasts qualify for the NEMA Premium Ballast program, you are more likely to have good quality. Here is a link that might be useful: NEMA Premium Ballast

I've been pouring over Rejuvenation, but I have no idea what would be good in that space - pendant, flush-mount, semi-flush, chandelier? Two lights, three lights, four lights? In a round arrangement or in a line? I seem to like the mission style type lights best, and I'm kind of liking the billiard-style kind, so I can get two or three lights in a row by the sink...but will that be weird with nothing underneath? I have 8' ceilings... I don't want it to be too low. And then what for the other fixture? Does the table make a difference? It seems that 90% of kitchens these days have islands, so in a kitchen with a table instead of an island, I have no idea what to do! I'm worried I won't have enough light if I do flush or semi-flush, but I don't want the fixture to hang too low. Any ideas?

Thanks everybody, that was very helpful!. Amazing how much more meaningful search results you get when you actually know the correct vocabulary. After some searches and discussion, we decided to replace the fluorescent light fixtures with similar LED ones for now, and to consider better looking lighting when we finally get around to giving the kitchen a facelift (which will take a while given the other things on the schedule). Lars, the color comment was very helpful because it turns out a lot of 4ft fixtures are made for commercial purposes or for garages and have much brighter, harsher lighting than desired for a kitchen. In case anybody is ever interested, this is the light fixture we have decided to get: http://www.homedepot.com/p/Hampton-Bay-4-ft-x-1-ft-White-LED-Rectangular-Ceiling-Flushmount-54647141/205331010