A few things:
1. Your OP doesn't really get into this very much, but what are the things you associate with your relationship with the Celtics, something different from the fan sitting next to you.
2. The C's sucked for years, now they're on the top of the mountain, and sadly they will someday return to being a crap team for awhile. In my mind, if you're going to honor their championship, it makes sense to honor those years when they are just a crappy team that you loved despite yourself. Perhaps incorporating images and themes that you remember during the lean years, this will make it fresh when they are up as they are now) and down. This will also make it a personal tattoo.
3. What does #17 mean to you, personally. I'm not just talking about basketball here...
4. Out of curiosity where are you going to get it done?
A little more info and you could conceivably come away with some valuable advice from this thread, but as you can see above, most people can't offer you an honest attempt at an answer to such a personal question without more info. If nothing else, it important to remember to steer as much away from convention as possible--just keep in you mind the tattoos everyone's getting of the plain ol' Boston "B" after the Sox won, and you can see what I mean.