I managed to get through a reasonable selection of daiquiris last month, and though some places revealed their ignorance by initially saying things such as "we can't make one, because we don't have any fruit", in general I managed to get good results with a bit of coaxing. The lime/sugar balance was all over the place, but none were really undrinkable, and it's really down to personal taste whether you prefer them tart.
Nowhere really stood out for the excellence of their classic Daiquiris, though a couple of places offered worthwhile variations. The Buena Vista Social Club has some new staff who seem more capable of living up to the expectations that their cocktail list sets, and their "Floridita Daiquiri" (with the reasonably traditional addition of Maraschino) is nicely set off with a palm sugar rim. I see that this place is on the market, so if it has new owners soon I hope that they continue this improvement in form. Newcomer Alice also does a very good classic Daiquiri, plus some very tasty variations involving apricots and plums. These aren't slushy frozen Daiquiris but good strong drinks with the addition of fruit purées, and they achieve a fine balance between fresh flavours and serious alcoholic content.
The drink for December will also be just right for summery weather, and has specific seasonal connotations that make it doubly appropriate for this time of year.