He and Brad Altman had to wait, literally, decades to get married and were some of the first people in line to do so when gay marriage was briefly legalized in California.
For Star Trek fans, Takei has freely suggested "Walter" as Hikaru Sulu's middle name, after fellow actor and friend Walter Koenig. Double awesome because when Koenig initially joined the Trek cast in the second season, he and Takei had professional tension (over fears that their characters would be reduced to Those Two Guys), but they ended up becoming good friends anyway as their characters became an iconic pair at The Bridge's helm.
Combine these two, and you get the fact that Walter Koenig was the best man at his wedding.
The sheer fact that millions of people look at his Facebook page every day to feel cheered up, when their days have been so depressing. Plus all the posts on his timeline that he gets every day thanking him for:
A) helping them embrace their sexuality and come out.
B) helping them when someone they knew come out (one dad says that thanks to Takei's example, he was proud to stick by his daughter when she came out).