Hi!
I don't have any bike suggestions for you, but I just wanted to welcome you to the forum. You have a wonderful outlook and are ready to do great things - just need the tools! I do know that a lot of ladies start with a hybrid bike before determining that they want a road bike. Mountain biking is great too, but unless you have good trails near where you live, there are more road biking alternatives most places. I am lucky enough to do both, and enjoy different aspects of both. Of course, I have four bikes, so that helps!
I hope some other gals here can offer you suggestions on specific bike models. The only advice I can offer is to go to your LBS and test ride as many bikes as you can and see which type/style feels right to you. And make sure to get a good fit. At your height, you probably won't need women's specific design, so you'll have lots of options.
Good luck, and keep on posting!!
Emily, just one state south
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow