Grand Wine & Spirits — Establishment and liquor store at 220 Connecticut 12, Groton, Connecticut.

Great selection and very reasonable prices. The staff is very friendly and helpful, being quite knowledgeable of products and able to give good selections if you can describe what you're looking for.
I'd also recommend joining the Beer Club, and take part in any tastings that they host. It's a $25 fee for the tasting, but after the event is comes back to you as store credit for that night, usable on anything in the store, not just what you tasted.