The only hotel within the borders of Zion National Park, the 41-room Zion Lodge proves sustainable practices can work in an old building. Built in the 1920s, and then destroyed by fire and rebuilt in the 1960s, it has the look and feel of a historic park lodge, down to the pine-paneled lobby. But the many small sustainable touches it incorporates make a big difference. It uses dual-flush toilets and low-flow fixtures, a 10,000-watt on-site solar array, LED nightlights, organic cotton sheets, an on-demand boiler, biodegradable and non-toxic cleaners, recycled floor carpets, a biodiesel-powered guest bus, an elaborate composting system, and bamboo floor entryways. If only all other national park lodges could follow its lead. Rates start at $175 per night.