Should I ?

I'd have the dealer change the timing belt and do the rest of the stuff myself. I don't believe that the ES engine is an interference type but you still don't want to get stuck somewhere do you? Any auto parts store will carry equivalent oil filters, I think the ES uses a PH3614 or equivalent, but don't take my word for it. Don't need to do anything more than what the owner's manual states. Lexus dealers provide very good service in most cases but it ain't cheap and like most car dealers they will try to sell you a lot of unnecessary over-priced services.

Do yourself a favor and pretend you have a Toyota Camry V6 XLE. (which you actually do) Most of the services can be done at the Toyota dealer for less money. Even a timing belt. Oil change could be done at the dealer for half price. 19.95. Your engine is the same as in the V6 Camry so I'm guessing the filter is the same also. You claim you want to hold the maintenance costs down by doing small things yourself, so why the heck are you getting an oil change for $40 at the Lexus dealer? Of course if you wish to fool yourself into thinking you are rich and naive, then by all means, let the Lexus dealer max out your credit cards. They might even pretend they are doing you a favor.

As far as timing belt, my 97 had 95k on the timing belt when I traded it in. Since it is an non-interference engine, doesnt' do much harm to delay a little. Recently there was a post of a guy that has a 92 Camry V6 with 300k miles and 120k was when the last timing belt was changed. Also original water pump which is incredible.

The $19.95 oil change special at the Toyota dealers has a fine print, "Toyotas only". Besides, the ES uses synthetic oil I believe, not dino oil that they use for that offer.

Funny ... ya never see a Lexus being serviced at a Toyota dealership. WHY is that? Some rule or policy between Toyota and Lexus?

I do, at one of three local Toyota dealerships in my area. I even asked the rep about it, and he says they will do anything short of major engine and all warranty type work.

That said, my wife (she drives an ES), won't go there, but I think I'll try their oil change the next time, just to see.

True, as long as you stick the the correct change interval. The interval specified in the owners manual is for the synthetic type and maybe a few owners might not notice it.