For the 90K service I would use a private/independent mechanical repair facility.
I just had the 90K service done at a local Lexus specialty shop....
I waited until 100K, which is cutting it a bit close as the timing belt was starting to fray at the seam.
In addition to the timing belt, they replaced the following: timing belt tensioner and idler, water pump, front main seal, serp belt, plugs, caps, rotors, all filters, all fluids (oil, trans, brake, rear diff, ps, coolant) , upper and low rad hoses, and a few other things. They also ran a full battery of tests including compression.
Total was $1381.
AFAIK, Lexus gets around $1200+ just for the timing belt and water pump.
Yes, this is expensive IMO but I didn't want to try the timing belt R&R myself....not worth the risk.