I'm getting a tattoo, what's the best spot?

Ok, so i'm getting my 2nd tattoo after 5years next weekend in Vegas (whoo hoo... Viva Las Vegsss) and i'm debating where to get it! I already have a medium sized one on my right back shoulder and i'm thinking the next one should be on my hip or side? I don't like the whole lower back thing... as they call it the "tramp stamp" and I need to put my tattoo where it's easy to hide. (For work purposes). I was thinking of getting a tattoo in the middle of my spine but i think that would clash with the other tattoo and as much as i want one on my foot, It just wouldn't work out! Any tips?