I'm also looking to replace the tires on my 2000 RX300, but not because of wear. Currently have Michelin LTX M&S tires (225/70R16). They were put on after I had ~8000 miles on the original Goodyear Integritys, at which point the latter showed really bad feathering. Dealer did a 4-wheel alignment check (so they said, but I just recently found out they didn't) and said they would let me put on new tires of my choosing. I like Michelins in general, and these tires are great in snow, but lousy in most other respects, especially wet traction and NOISE! I want to get rid of them mostly because of the noise, which has gotten worse with time.
I looked into all the tires Tire Rack offers in this size. Read the reviews. The absolute top tire (#1) of all the tires in the (light truck) class is the Bridgestone Dueler H/L Alenza. People who've owned them actually rave about them. The only problem with them is price. Tire Rack's price is $116, and that's before S/H, mounting/balancing, tire disposal fees. After adding all that in, it's about $143/tire. While I still weighing my options, I'll probably just swallow hard and get them.