To JPEG or not to JPEG
It has become a truism nowadays to say that although our most important images should be shot in raw format to preserve maximum potential, when it comes to casual images (family snapshots and such), shooting JPEG makes sense to save time and disk space. After all, the saying goes, we're not going to be making large prints of those less critical images, so why bother? Some have gone as far as to suggest embracing JPEG even for serious work—so long as the photographer follows a number of precautions(1).
I'm going to risk making myself look like a dogmatist here and call this utter nonsense. If my miserable two-megapixel cell phone camera could shoot raw, I would. It's not a matter of dogma to acknowledge that although the JPEG format produces smaller files, it necessarily produces worse files—and not necessarily for the reasons you think. No amount of open-minded investigation of "the JPEG option" (regardless of how much effort the camera's manufacturer has put into it) will change that fact(2).
The JPEG option only has two arguments going for it and I will show how they do not withstand scrutiny.
Shooting JPEG saves time
Do you open every one of your images in Photoshop and proceed to do careful curve adjustments for tone and color as well as extensive dodging and burning, followed by a slew of adjustment layers with masks to perform local corrections? Me neither. The fact of the matter is that "post-production" doesn't have to take a lot of time (especially for less important images)—and generally doesn't.
Yet, going through the sliders in Lightroom's "Basic" panel can, in a matter of seconds, have a monumental effect on an image by nailing a more appropriate white balance, normalizing the overall brightness, extending the tonal range and pinning the contrast. It would be a shame to give up that flexibility (even for casual shots) just to save a few seconds.
It also doesn't help to say that because you believe the in-camera rendition happens to be close to where you'd like it to end up (therefore won't require aggressive manipulation), JPEGs are good enough. Wait, what? So now taking a few seconds to adjust a raw file is too much of your time, but taking a few seconds to adjust a JPEG that you've somehow managed to bring close to your target at capture time isn't? Either you do post-processing (in which case, you lose nothing but gain a lot by shooting raw), or you don't.
And there lies the fundamental problem of how time-saving it is to shoot JPEG: it isn't. There are so many steps in the image processing pipeline that could go wrong that the odds of getting precisely what you want are vanishingly small. To produce a JPEG, the camera has to (among other things, and not necessarily in that order) do demosaicing, apply a gamma curve, compute noise reduction, perhaps do lens corrections, apply a white balance, apply a tint and a saturation adjustment, apply sharpening, convert to a smaller color space, before converting to 8 bits per channel and doing a lossy compression.
You can, to a certain degree, adjust many of those parameters by fiddling in your camera's menus. The problem is that not only are all of those parameters spread at different locations in the menus under dubious labels, not only are they very limited in their precision, but you have to try to do all of this using the small unreliable LCD on the back of your camera—under changing light conditions! That is clearly the worst possible time to be doing this properly, especially when the action is going on in front of you and you have only moments to capture it.
Shooting raw means having to care only about exposure (aperture, shutter speed, ISO). Talk about time-saving! Everything else becomes entirely meaningless at capture time, which means it is impossible to forget or improperly configure any one of the other parameters, so you can concentrate on getting the shot. It's not a matter of being sloppy, it's a matter of making the effort when it makes more sense to do it. Sure you might spend some more time in post, but that's only because you've saved a lot more before.
I'm not one to judge: if you enjoy painstakingly configuring your camera's parameters in the field, I don't want to take that away from you. Just don't tell me that shooting JPEG saves time.
Shooting JPEG saves disk space
(Yes, disk space is cheap, the argument is pretty much a non-starter, but let's say you really want to keep it to a minimum ... because of a reason.)
You believe you don't need to have the full raw file for casual shots you won't be making large prints with, so why waste disk space. Fine. Do your adjustments on the raw file, export it as a good JPEG, and throw away the raw! Understand that the "JPEG" part of the equation is only adding insult to injury: the biggest problem is not so much that it's compressed, it's that the image has been "baked"—the camera (with some of your input) has already taken all the processing decisions and thrown away the leeway. Shoot raw to save time at capture time (as explained before) and preserve the margin of error, but once you've nailed the final image and placed it in your photo album, feel free to throw the negatives away! (I wouldn't, but it would be reasonable, if disk space was a concern for you.)
But perhaps this is not the most significant way to save disk space. There is a little known technique to recover tons of disk space, an obscure art that seems to have been lost to the days of the light table. Shockingly, not only does it save space (which allows you to keep the raw files—hooray!), but it also tends to improve your entire photography in the process. This arcane methodology is known as (get ready): editing your damn work. Not every single actuation of the shutter deserves to be preserved and archived for future generations. Sit down in front of your day's images and delete the junk.
The editing process can even begin earlier, when you're still out there with your camera, by following this very simple rule: Look more, Shoot less.
(1) Exposing-to-the-right has never been an appropriate strategy for anything but raw capture. Whoever suggested that was simply mistaken.
(2) Let me be clear that I am talking about people who could shoot raw, but choose not to. Obviously there are some who cannot shoot raw for practical reasons, although they do it reluctantly. Those people include the NFL photographer who is going to fill his camera's buffer and memory card too fast, the time-lapse shooter who has to capture 3000 frames this afternoon, the war photographer who has to load the images on his dusty netbook and send them via a satellite link in less than 10 minutes worth of battery, my mom, the guy whose oddball camera shoots an obscure format that no decent raw processor supports (yet?), etc.
Naturally, it's also perfectly reasonable to be happy with JPEGs if you simply do not care that you are giving up a lot of image quality/potential—but then the discussion is over.