Beatrice alludes to her views on marriage in her first exchanges with Benedick -- "I had rather hear my dog bark at a crow than a man swear he loves me" -- but it is in Act II, Scene i that she really gives out her feelings about marriage. Some of her comments in that scene:
Just, if he [God] send me no husband, for the which blessing I am at him upon my knees every morning and evening.
So...away to Saint Peter...; he shows me where the bachelors sit, and there live we as merry as the day is long.
Later in the scene, she watches her beloved (and younger) cousin Hero become engaged and comments:
Thus goes everyone to the world but I, and I am sunburnt. I may sit in the corner and cry "Heigh-ho for a husband!"
She is speaking to the Prince, Don Pedro, who gallantly (if somewhat obscurely) asks if she would have him as her husband. She refuses. This awkward moment is a very telling and often discussed one, but it certainly shows that Beatrice is not in very much of a hurry to marry anyone. For what better alliance could any woman dream of than to marry a Prince?
We later discover that, once she overhears that Benedick loves her, she is willing to throw all thoughts of bachelorhood out the window and become his wife, revealing herself to be the ultimate romantic, willing to marry only for true love.