Since I love cucumber, I'll suggest cucumber cooler. Some of Hong kong's best cocktail bars served this one, the reason why I loved this drink. It is consist of cucumber, sliced crosswire, garnish, fresh thyme leaves, vodka nad simple syrup. It will really help you ease the thirst brought by summer =)
Two things I can't live without in summer: A very cold beer (German preferably) or a delicious Spanish Rueda white wine. Also served very cold! Yum!
But when I'm craving something sweeter, a "Tinto de Verano" is my first option.