Heath has a good suggestion on product. I have two or three customers in the last year that opened stores and completely ran out of coffee during the grand opening! In order to bring people to the store - I have had customers bring in the local fire department, the mayor, combine the opening with a local fundraising or get a local radio station to broadcast from the location. Also, if you use an electronic gift card, do everything you can to get them in the habit of buying them upfront - they get in the habit and you lock in the money.
Congrats on making it this far and definitely let us know how the grand opening goes!
Do cheap doubles all day. It's a great way to show your shop is about quality and will win you many regular espresso drinkers.
Dont forget to join your Chamber of Commerce. They will in our town do a ribbon cutting and newspaper time for it. Good luck.