Yay! I'm glad you've decided to get the 30, especially as you said you like bigger bags and to me the 30 isn't even that big - it's the perfect size. Choosing between Mono and Damier I guess is a personal choice, but Mono might be nice what with it being your first LV. Let us know what you decide!!!
I know what you mean about going into LV, from the outisde it can look a bit intimidating to the first-time buyer. I just went in on Saturday to buy for the first time from the store (as usually I use the website) and everyone was really lovely and helpful and I felt stupid for thinking it would be anything different. I find using their website really helpful as then I can compare bags, size up the prices and then I know what I'm talking about too! Buying online is great as they have really good service, but getting it from the store is a fab experience also.