Signature Cocktails

My fiancee and I have decided to do two signature cocktails one which will be the drink we had on our first date a gin and tonic and the other a spiked prickly pear limeaid with tequila. For the latter the limeaid will be premixed i'm debating whether to pre-spike it or have the bartender do it also should we do it before. Which brings me to my next question, either way what containers could we pre mix it to make it look cute? Would it be best to talk to the bartender or caterer about that?