I recently acquired a 2000 es 300 with 115,000 miles.Is that considered high miles for a lexus even though It has been well taken care of, or can I expect to enjoy this car without any major problems for a long time to come?

you have a 2000 with 115K ... i got a 93 and 204K and i'm pimping... even tho i need to get my A/C fix up.. i'm still pimping with all the windows roll down. and have all the belt and oil check/change. and you're enjoy it for another 115K

As long as all the major maintenance work has been updated (incl. timing belt, water pump, drive belts, all fluid changes), plus keeping up to date with your oil changes with NO sludge problems, you should be OK for another 150K miles or so

I have 107,800 miles in my '01 ES, and it drives and looks beautifully like a brand new car out of the showroom