Hi Zoe and congratulations on the upcoming wedding! I don't think your idea is tacky at all. We had a beer and wine open bar with traditional and passion fruit sangria as our signature drink (it was a hot summer night in Puerto Rico!). I think sangrias are also very popular right now and more of a surprise and exotic element than the mojito. You can also serve a white sangria with strawberries on the bottom of the glass to fit your theme? Regardless, I don't think there's anything wrong with your option. Good luck though!
No I do not think it is tacky at all. Beer and wine is a safe bet and it is better than no drinks at all. I do like the idea of choosing a signature cocktail, that seems really fun. I would choose the type of alcohol that you like first, such as vodka, rum, whiskey, etc. Once you have that narrowed down it will be easier to find one cocktail that you like. Then check out websites for your favorite alcohol brands like www.absolut.com. They all have sections with drink recipes. You should be able to find something yummy and that will fit your color scheme.
Besides the possible signature cocktail suggestion I would stay out of the argument. Let them come to an aggreement, they will work it out.
Beer and wine seems OK to me. My bff's wedding had beer, wine and sangria. And I think you could pay if you wanted a mixed drink. I dont think anyone minded. I can see how maybe your dad feels like it wouild be an "embarassment" to not have a full open bar. But I would let your parents duke it out. If you would be happy either way, then I'd stay out of it!
New Jersey: We have dumps, bays and cement boots and we know how to use 'em