Definitely get her spayed, especially if you don't want unplanned pregnacy!
I got Venus spayed yesterday. My vet sent me written instructions home with me. Just to keep her quiet, and some water later in the day, and no food till this morning, and no hopping on furniture for a week.
I got really worried about her last night, but then again, I remembed they wanted to keep her overnight "cause you might not want to see them so out of it" that first night. I figured with all the resting she was doing it was pretty normal. I gave her water through dropper thing, and some neutra-cal. Later last night (against vet orders) she wanted some food, so I gave her about 7 pieces of her puppy food. She's done fine.
I put her crate on my bed last night, lol. I was even prepared to sleep on the floor with her if necessary
Today, she's out of the crate, but in her bed, and doing fine. Still a little groggy, but she's ate some today on her own.
I think this is scarier for US than it is them!
Just make sure they use the Isoflorane and NO barbituates. Most vets these days don't use barbs anymore anyway.
I'd definitely get her spayed if I were you. It sure keeps down diseases later in life. I seen several on here that are having problems with their dog later in life for not having them spayed.