I liked my first Avalon so much that I bought another in 2000 and we've put 330,000 miles on the pair. Both are nicked up but they still run fine (2008). In 19 (combined) years of use I've had only ~$3,000 in repairs (other than an accident, tires and oil changes). Cons: Weak in snow. Steerling column leak (both cars - use sealing fluid). Goes through tires too quickly. Toyota's known for quality and reliability and that's exactly what I've experienced. In 2007 I purchased a 1986 Corolla that runs fine. I now need a 4th car and it will be a Toyota. I still feel that I made a solid purchase every time I start up one of my Avalons.
Quality and reliability. Quiet and smooth ride (no noise as others have mentioned). Roomy and comfortable. Good gas mileage.
Variable speed wipers. Improved steering column (leaks). Faux wood trim items on the second Avalon have flaked off.