I figure, if you're drinking less than 64oz of water per day, you can just kind of assume that you're a bit dehydrated. And more water than that is really better, especially when you're pregnant.
As for getting enough water... I drink water from a 16oz glass. I try to have a minimum of four per day (equalling 64oz), and more is definitely better. If plain water is hard for you to drink, there are flavorings and things that you can add to it that may make it more bearable. I just had a friend telling me about this stuff called Mio... its zero calories and you add a few drops to your water and it tastes nice. There's a few different flavors of that... but even if you drink 64oz of lemonade per day, its better than not drinking anything at all. Juice does count towards your water amount.