The homoerotic subtext of the Rat Pack bond is obvious -- today, anyhow. They were all about male bonding, with the intensity and physicality of romance. And audiences cheered them for it.
Some of them were bisexual in real life. Others were homophobic -- even more than what one expects in the homophobic 1960s. In order, from least to most gay-friendly, they were:

5. Frank Sinatra, age 45 in 1960 (top photo), The Chairman of the Board, a teen sensation of the 1940s, still releasing old standbys and finding a whole new generation of fans. He starred in one of the more homophobic movies of the 1960s, The Detective (1968), and was reputedly so homophobic in real life that he threatened reputedly-gay Johnny Mathis.
4.Joey Bishop, 42-year old comedian, sitcom star, later talk show host. Married during the days of the Rat Pack womanizing, kept to himself a lot. Bff of future talk show host Regis Philbin.
3. Dean Martin (left), age 43, whose comedy act with Jerry Lewis in the 1950s had distinctive, perhaps intended homoerotic undertones. In the 1960s he released some popular songs, had a comedy-variety show and starred in the detective-spoof Matt Helm series. No evidence that he was aware that his son, Dean Paul Martin, was bisexual.
2. Peter Lawford, 37 year old former child actor, later a tv star (he was on The Doris Day Show). Everyone thought he was gay; Louis B. Mayer went as far as to order testosterone injections as a "cure." Got married to Pat Kennedy, the future President's sister, over the objections of her father -- he didn't want his daughter married to a gay guy. Reputedly had relationships with Tarzan Gordon Scott, Rock Hudson, and Merv Griffith.
1. Sammy Davis Jr., age 35, "Mr. Show Business," dancer, singer, actor. Converted to Judaism. Kissed Archie Bunker on a famous episode of All in the Family. Bisexual, tended toward men, preferred clean-cut all-American types. Closeted to the other Brat Packers (except maybe Peter Lawford), but opened up to teen idol Paul Anka, whom he thought was gay (everyone did at the time). Mentioned being bisexual in print as early as 1978. Died in 1990.