You'll find a great article on the Mexico About.com site on outlining a Frida Kahlo and Diego Rivera Tour of Mexico City. Read on here to learn more about visiting the Frida Kahlo Museum, or Museo Frida Kahlo: La Casa Azul (Londres 247, Coyoacan, 55-5554-5999).
Coyoacan is about 10 km south of Mexico City proper and the hotels in Polanco - you can get there by cab (it takes about 20 to 30 minutes in traffic), or you can catch the clean, affordable, safe, and efficient Mexico City metro, taking it to the Coyoacan stop and walking about 15 minutes to the museum. Kahlo's former home, Casa Azul (literally "blue house", the home and its exterior walls are indeed painted in a striking shade of blue), is home to the museum. Admission includes a tour through the rooms, which are hung with Kahlo's paintings and packed with furniture, belongings, photos, and documents that pertain to her life. You truly get a sense of the artist walking through this impressive home. On leaving the final room, you'll find yourself in a leafy and expansive garden in which you'll typically spy two or three friendly cats roaming about. A pathway leads to a charming museum cafe with outdoor seating, and an additional exhibit space where rotating shows are held - these tend to be quite good sometimes rather provocative, such as the "Smoke and Mirrors: Frida Kahlo's dresses", which was presented by the museum and Vogue Mexico.
From Museo Kahlo, it's just a few blocks' stroll through this elegant residential neighborhood of brightly colored colonial houses to reach Museo Casa de Leon Trotsky (Rio Churubusco 410, 55-5554-0687), the home in which the dissident Russian revolutionary lived out the final years of his life, and in which he was slain by an assassin with an ice axe. On a tour of the museum, you'll see the rooms of the house furnished virtually as they were when Trotsky was killed - it's an eerie and compelling sight, especially bullet holes in his bedroom wall (from a previous, failed attempt on his life). Trotsky was a fried of Rivera and Kahlo, and some memorabilia in the house pertains to this.
From Museo Kahlo, walk south a few blocks along Ignacio Allende, stopping at the bustling, if sometimes chaotic Mercado de Coyoacan, a great place to stop for a delicious snack - head for informal food counter called Tostadas La Chaparrita, where for the equivalent of $3 or $4, you can feast on tostados piled high with fresh ceviches, octopus, marinated beef, tinga (shredded chicken), and more. Walk a few more blocks south, and Coyoacan's beautifully landscaped central plaza, which is home to a number of cafes and bars, many with sidewalk seating.
You can catch a cab by the Plaza for the 10-minute trip to the neighboring village of San Angel, which also has a lovely Plaza San Jacinto that on Saturdays hosts an enormously popular art market. From here, it's a 15-minute walk (just ask for directions - it's easy to find) to Museo Casa Estudio Diego Rivera y Frida Kahlo (Diego Rivera 2 Altavista, Álvaro Obregón, 55-5550-1518), the striking modern building in which Rivera and - mostly during the years of their marriage - Frida Kahlo worked and lived. Here as with Casa Azul, you can walk through the entire house, enjoying a glimpse into the lives of both artists.