I agree with karlbadmanners - and good for you for looking at multiple shops. So many places show "[X] years combined experience!", but when you stop to divide out how many years per artist... well... not all tattooists are created equal.
Make sure your artist can do what you want. Some are good at drawing people, but horrible at animals. Some have a talent for drafting the mechanical, but couldn't make an organic slime mold to save their souls. Everyone has their own skills.
Biggest thing to remember with your design: if you're not happy with how it looks - DON'T GET IT. That sucker'll be permanently engraved in your flesh, and there's NO REASON it shouldn't be perfect! You need to take the time to tweak it to a level you're happy with. Tear through those tattoo magazines for styles you like, or a method one artist uses to color, etc. If your artist is good, they'll be able to utilize those materials to help draft out just what you want.
I know I'm ranting here - my Mom has been a tattooist for the last 28 years. I've seen a lot of horrible pieces come walking through the shop doors, their owners looking to get them fixed or covered up. I understand wanting to get one while you've got the "permission" from da wife, but patience is good. It took me about 3 years to design the piece on my back. The tweaking paid off - believe me.
