I have personal experience with the two cars that the OP is interested in - too bad I didn't see this thread earlier.
I have a 1997 LS400 with 155,000 mile that I've owned for 5 years and I've racked up most of its miles. I'll note that it has sportier (firmer) KYB GR2 strut inserts and I have good tires on it, Yokohama V4S, giving it excellent ride control and cornering. I've driven floppier LSs that I didn't like as much. The right tires make such a difference, and good shocks are the most effective suspension modification you can make, for most cars.
Last September I got rear-ended on the freeway pretty hard. $5000 of bodywork took about a month, during which time the at-fault driver's insurance company provided me with a 2009 rental Camry. It was of course just a 4 cylinder. It's impressive how adequate 4-bangers are in large sedans these days, the power and torque is far above what economical engines used to make. However, I wasn't blown away by the fuel economy. There is a point of diminishing returns, particularly if you drive a car pretty hard, and I only netted about a 3-4 mpg increase over my usually 21-22 mpg in the LS. Coupled with the drop in gas cost by filling with regular instead of supreme, the Camry saved maybe 20% in fuel costs, which I did not think was worth the loss of torque. Had the Camry had the V6 I bet I would have been fully satisfied with the power (equal hp, a little less torque than the LS, and a couple hundred less pounds to move), but the gas advantage would shrink in half and I would still miss the smoothness of the LS V8.
Now on to the interior and here is where the Camry really suffers, as it must since it is built to compete at a lower price-point. The LS has high-quality materials, smooth edges, beautiful and elegant electroluminescent gauges, leather seats (mine are still excellent due to leather conditioning at regular intervals), and every part that moves has beautiful detents. On the other hand, the Camry interior is full of plastic and rubber parts that look ugly and feel cheap, and while some of the moving parts feel alright, the overall sensory experience is unsatisfying. I was really sick of the Camry and missed my Lexus by the end of my month. The seats were not as comfortable for me (I am 6'1", 205#) and made me uncomfortable on drives longer than an hour. I missed the LS's beatifully weighted steering, with its ingot-like solidity, and the feel of the polished leather steering wheel. Every time I shifted the Camry, the plasticky shift knob felt tacky as it moved through the gates, whereas on the LS, the spring loading and gates for the shifter feels so much richer, not to mention the pleasure of handling the polished leather knob. The Camry's stereo had as much bass as the old 97 Nakamichi system, but didn't have the quality of sound in the mid and high frequencies that makes the LS stereo such a pleasure to listen to on an hours-long drive. The doors on the Camry shut with a high-frequency ping of an economy car, whereas the Lexus doors shut with a rich bassy thump befitting a luxury car.
Styling-wise, I think the LS has a beautiful and classy shape. On the other hand, I think the 2009 Camry has horrible hand-me-down styling from the already revolting Bangle-era BMWs.
The Camry has a good ride - for an economy sedan. But it is not nearly as smooth (or quiet) on the highway or over rough pavement as the LS. The Camry's handling is as demoralizing as I expected it to be. The problem is not lack of grip, but lack of fun. Like all modern sedans, the Camry can achieve adequate cornering speeds, but it has a dreadful conflagration of nose-heaviness, numb steering, front wheel drive, squeally non-performance tires, and excessive understeer. My LS, with good struts and performance tires, is far more lively and fun to drive. The rear wheel drive layout and torquey V8 allows me to transfer weight to aid turn-in and I can roll on the gas earlier as I exit a corner, whereas the Camry's front tires are loaded up with double-duty to accelerate and steer its nose-heavy chassis. The Camry felt bouncy and cheaply suspended, whereas my 155K, 12 year-old LS feels far richer in its handling. The Camry's annoying handling traits would be worse with a heavier V6 in the nose, and more hp & torque being fed into those squealing front tires.
Midsize cars are now pretty large and the Camry was only a little smaller than the LS - but it is smaller, if that matters to you. I thought its size was adequate, so no real demerits there.
To me, the 2009 Camry was a penalty box and I would not ever own one (4 cyl. OR V6) if I can help it. I am not going to tell you that the LS is the car for everyone, because there is no such thing, but I would recommend getting it or another used luxury sedan over a new Camry. I was so glad to get my LS back from the bodyshop. For new Camry money, you could get a used LS430 that is a better luxury car than my '97 LS400. If you get an LS400, get a '98-'00, which have 30 more hp, a very needed 5th gear in the automatic tranny, and auto up & down for all the windows.
