I do oil analysis on our entire fleet, just to monitor wear levels. Benefit to me, I get it for free through my work, otherwise figure out an extra $20 per oil change if you want the info. It's taught me when I need to clean my air filter, when my cruising tune is too rich (as is the Supra's case, plan to work on that this spring / summer), among other things.
Of particular note, and perhaps the most valuable aspect to oil analysis, the ability to extend the drain interval. In perhaps the most impressive display of oil longevity I've personally seen, my wife's 2006 Mazda3 with the 2.0 MZR engine. We have run Mobil 1 0-20 in it for as long as I can remember, she rarely lets it warm up much before setting off, we don't treat it as some super special car, apart from just taking care of it, fixing what needs fixing... usually. I let her drive on it a bit longer than I usually do last year between oil changes, and she put 15,161 miles on it on the same batch of oil. Didn't burn any, didn't have to add any that I can recall. The report after sending in a sample?
" NORMAL WEAR METAL READINGS. OTHER ANALYSIS READINGS APPEAR TO BE ACCEPTABLE. NO PROBLEMS PRESENTLY ASSOCIATED WITH THIS SAMPLE. CONTINUE SAMPLING AT THE NORMAL INTERVAL. OIL AND FILTER CHANGE NOTED"
Yeah, I'll take that. The report includes a ppm amount on 17 elements, as well as water / antifreeze presence, and viscosity at 100° C. It's good info once you learn to read it. =)
Would I do it on every car in the fleet if I didn't get it for free? Probably not. But on my Supra, a car with an engine that is still in sorting phase, and one that I have a stupid amount of time, effort, and money tied up in? Oh yeah. That one would be worth the extra cost.
About the only cars I would recommend running a sample on in the realm of more normal cars would be ones that are exhibiting signs of strange operation, fluid loss, or bad reputations for oiling or bearing issues. Other than that... I'd probably only run it on the fun and fancy stuff myself, and stick to a reasonable oil change interval. Quality filtration helps too. Not trying to advertise for any particular brand here, as nobody is paying me to, but in the event someone asks what filters or oil I run, I tend to use Donaldson filters on all our cars, and everything from Mobil 1, Rotella T6, to Redline, depending on the car.