You mentioned a key factor, maintenance, because catch up can be expensive. However, once you have caught up, the 100 will be remarkably reliable. It is a huge step upward from a RAV4 as far as heavy duty construction is concerned, but it is also a great family vehicle. While maintenance is a huge factor for me on a used vehicle, rust is a real killer. I had multiple Previa vans and they are very durable vans, but I got an All Track that had some rust, and eventually the rust won. We still have a 94 that is running fine. The LC/LX is built to last longer than any other Toyota vehicle, but rust can prevent maintenance because of the lack of a solid support for a replacement part.
The AHC experienced some problems in the early years, primarily for lack of knowledge in proper maintenance. The first time I learned that the AHC fluid needed to be replaced at 60K was on ih8mud. Dealers seemed to think it was a check function instead of a replace. Some techs, hopefully non-Lexus, apparently would substitute brake fluid and destroy the AHC system. In the past 5-6 years, all dealers I have been to seem to be quite aware of the proper maintenance of the AHC. I think when Toyota added AHC as an option to the LC, service technician awareness took a giant leap forward. I have 244 K miles on my 01 original AHC system (only front shocks replaced); but AHC fluid has been replaced every 60K.
I have noticed a tendency of many owners to maintain a vehicle the first 100 K miles, then relax and be inconsistent if not negligent after that. Key indicators of attention to maintenance and care for the vehicle are found in the type of tires they bought, the wear of the tires, condition of the seats and interior in general, missing or broken components, and the number of burned out light bulbs. Do the brakes stop well; smoothly, consistently, and quietly? Does it ride like tires are out of round?, does it pull to one side? Look at the underside- does it show minimal rust, is everything intact? I avoid vehicles that install high flow air filters such as K&N because they are ineffective, allowing fine particles into the intake/engine and oil particles to coat/contaminate the downstream electronics/sensors. The Toyota oem engine air filter is a good value supporting long wear engine life and proper functioning of the sensors and electronic controls. Just be sure to replace it when needed - at least within 30K miles. These all give clues to the maintenance commitment of the previous owner; and how much work you will need to do to get it into a fully maintained status.
200-300 K miles are still relatively young for the LC or LX; they were designed to be durable and last for at least 25 years. Many will show little wear even though 10-15 years old, and should have little reduction in the ride quality. New design and features were added to the 100 in 1998, 00, 03 and 06. While all the 100 series are reliable, I have tended to look for 01/02, 04/05, and 07 models because they represent more mature models for newer features. Since you intend to keep the vehicle for a long time, the initial cost outlay is not as significant when considering the total long term cost-benefit ratio. In general, get the newest model with the features you want that you can fit in your budget.
There are some features about the LX that made it attractive over the LC. My wife is short, so the AHC was a plus for entry/exit and loading items. I learned to appreciate the AHC quickly on our many long trips, because the LX was always at the same running level regardless how much we were loaded up. The ATRAC and VSC are great for safe travel in all seasons and weather conditions. My wife has asthma, so the auto recirculate with smog sensor feature was big; so was the cabin air filter (some LCs had the filter capability, but were not utilized). The Levinson audio system was available in the LX starting in 01 - a very nice upgrade. The interior was similar, but nicer in the LX. The headlights in LX were better.
I drove many used 100s at many dealerships over the years, and got so I could tell quite a lot about one from how it looked, smelled, and drove. I looked in nooks and crannies for tell tale signs of previous conditions - and to make sure all the seats work rights, etc. There is a hierarchy in the used market. A dealerships will have its own internal market and may have its own auction to keep the "best" used cars inside their own brand. If you work with an internet sales person, you can describe what you want, and they will act a bit like a broker in finding it. Lexus can access their internal network of vehicles that have not gone out to a general auction yet; most of these have been maintained at Lexus and have done well in the regular Lexus inspection to prep for sale.
Low mileage can be a negative factor. It can be your first clue it is from the north country, and may have rust issues. It can also be an indicator of heavy city use; thus indicating a higher level of wear. Maintenance should reflect both time and mileage factors; plus the way it was used - city vs highway.
Enjoy your search. Have patience, some people have taken consistent good care of their LC/LX. You want one of those.
