Display for outside (sun)
To be able to see it in sunlight you should use a 7 segment LCD display like this:



Image from alibaba.com

To see it in the dark, choose one with backlight. 

To save pins, you could use a BCD to 7 segment decoder like CD4511. For each digit you need 4 instead of 7 pins. This makes it also easier to interface with the microcontroller (write directly the value to be displayed to a 4 bit port for each digit).