Heatwave

I seldom drive my wife's 2007 E350 Sport ... 84,000 miles. But I drove it earlier today ... highway trip ... and noticed that it seemed "noisy." Louder than I thought I recalled ... road sounds, but it's not the highway ... not exhaust or engine sounds. Tires are properly aired ... exactly what the label inside the gas filler door calls for ... and appear to be wearing evenly. What are the "usual suspects"--wheel bearings, differential, driveshaft couplings? Any tips or suggestions for eliminating the possible sources, one at a time?