I am so glad that I purchased a 7 year/125,000 mile platinum warranty from Toyota on the 2012 Toyota Highlander.With today's vehicles IMO having an extended warranty is a smart move. I also like the idea of buying a warranty after 100,000 miles. There are warranty companies that cover you for 5 years and almost to 200,000 miles for only a few dollars.
As for the maintenance on the vehicles, I am in agreement with some of the previous posts, but only if you are very handy and can use equiavalent fluids as the Toyota fluids are very expensive. There is really not too much in drain/fill on the coolant, tranny, and rear differential. The brake fluid I do a complete flush in 30 minutes with a kit and $6. There are plenty of equivalent fluids for about a 1/3 of what Toyota charges, you just have to do your research and find the same manufacturer without the Toyota label.
Everyone treats there vehicles differently and if you plan on selling your Highlander privately, the more you spend on maintenance & (please keep good records), the more you will get on the resale and the quicker you will sell the vehicle. The water pump sounds like it is a PIA if I had to do this myself. Good luck to anyone that has to do this on their own.