For the most part, Sinclair Lewis tends to keep his writing nice and readable. You don't become a best-selling author, even in the 1920s, unless most people can understand what you're talking about. But every now and then he'll totally sound off with some really dense and poetic description. Take, for example, this description of Martin leaving a village in the Caribbean:
They sped out of the capital by white shell roads agonizing to the sun-poisoned eyes; they left the dusty shanties of suburban Yamtown for a land cool with bamboo groves and palmettoes, thick with sugar-cane. (34.1.3)
Now that's some vivid writing. But don't worry: Lewis is selective about when he brings out the poetic big guns like this. He knows full well that you can't redline the engine for an entire book. A reader needs to pace herself. So even though there are some densely eloquent passages, the book goes down as easily as a spoonful of sugar.