We have a Gay Grndson,so are (despite our age) quite Au Fait with the Gay Scene.
He says that (despite never having stayed at the Amsterdam himself) he has heard only good reports of it.
Gay guys are very female friendly,so problems there.
The only slight problem might be that the Amsterdam can have quite a few Lesbian guests,who (you being female) might come on to you.
You only have to make it clear you are str8 and I feel sure they will back off.
At least having a Gay/Lesbian atmosphere you will have fun,unlike some of the fuddy duddy hotels in Brighton.