That sounds like a great place to get it (not too obvious, has a really good meaning) I suppose the best thing might be to talk to a good tattoo artist and see what they say about stretching and what that would do to the kind of tat you are thinking of getting and the style of writing you want
The best places for not stretching are places with lots of bone, and not much between the bone and skin(shoulder blade, ankle etc. Maybe across your back would work?) But stretching is really only an issue if you are going to gain a LOT of weight, not just a little, if you lose weight it can alter the shape of a tat but less likely.
Also with writing it might just make it look more like cursive writing if it ever stretched, instead of a picture which might just end up looking like a blob