Make it a lounge your customers feel welcome in first and foremost. If you're going to make it a theme decor, make it a cigar theme decor. Not a sports team, not a nationality, etc. You want to attract the widest possible audience.
If you're going to have a membership, make it worth buying other than the typical 10% discount. Could be a free cigar each month, member-only events / outings, member appreciation dinner, etc. Make it so that people WANT to be a member.
Have things for the members to do...TV / DVD player (no porn...never know who's going to walk into the store), Satelite Radio, Games, etc.
Sectionalize the seating. Sometimes I don't want to talk to everybody and I don't feel like shouting over another conversation. If I'm with 2-3 friends, I might want a little privacy.
Have a nice selection of cigars...sizes and brands.
Mark the boxes for strength (not every customer is an expert).
Enforce the policies equally and from the start.
Drinks (coffee, bottled water, etc.) is a nice touch. Alcohol....I'd make it BYOB, but that's just me.
Most important, be engaging to your customers. I have one B&M up here that I've shopped at just because of the selection. The owner never comes out of his office. If you have a question you ask the counterperson and they relay the question and the response. I've never been greeted by him, never seen him or anything. But they're the only store in the area that has Opus and HTF cigars.