I was in the same exact situation this weekend when I bought my Speedy 30 in Damier.
At first, I really wanted it in Mono, but the more I thought about it....I drop stuff, spill stuff (we're all human, after all!) and live in a wet, snowy, humid climate (lovely, huh?)....so I decided the Damier was a more practical choice for me. I don't necessarily like one more than the other....but I am loving the chocolate leather on the Damier!
I agree with those that say that a bag in mono is an ideal first bag, but I guess I wanted my "first LV" experience to be a special one, and I didn't think that stressing about the vachetta, rain spots, and uneven patina on my first bag was the best way for me to go.
I think I will eventually end up with a mono bag of some sort, but for now, I am loving my Speedy in Damier, and I think I will get a cles or cosmetic bag in mono, that way I don't have to worry as much about it, while still having a mono item.