For beauty & photography, Wharf & Georgetown Sightseeing Cruise (City Cruises) is hit or miss.
A relaxing, breezy way to see the monuments and Georgetown waterfront from the water on a humid afternoon — City Cruises runs a narrated Potomac sightseeing trip from Transit Pier at The Wharf. The honest catch: the monuments sit back from the river, so the views are more pleasant than spectacular, and you're paying ~$30-45 for the breeze and the narration as much as the sights. Capitol River Cruises out of Georgetown is the smaller family-run alternative.