Just got my 03 RX back from its 100,000 mile service today, felt lovely to get back into it. I knew it needed doing soon but my hand was forced when the water pump sprung a leak on the motorway, fortunately I had some water to put in the radiator and was able to get the car safely home and then to my local garage who carried out the service, replacing the water pump as part of it. We get a lot of people on the forum asking about potential mileage for these cars, well when I was talking to the mechanic he wasn't remotely peturbed by my rx's 102000 miles, he said they are good cars and will last if the fluids are replaced when they should be.
I had been quoted a little over £1000 by a local lexus dealership for the 100k service, and been assured that it was a very good price. My local garage did the job for considerably less than that and I have every confidence in them - I have used them for some time now.
If you are in the Manchester area the garage is DJ Autos in Oldham, check out their website for address, etc.