If you want to show more information maybe you should use an SPI TFT LCD screen.You can add a light intensity sensor for automatic screen brightness.
If you want to go on battery ESP8266 isn't a good choise. I use ESP8266 for the same reason, NTP time set, but, maybe you can use an Arduino pro mini (with some modifications), an DS3231 RTC and an ESP8266 as a WiFi shield that you turn on only when you need set time. There is a sketch for ESP8266 so it became a WiFi shield or it can be done with a sketch that, when the ESP8266 is turned on get NTP time and print it on serial. You can turn on ESP8266 once a day.You have to remove all small leds in RTC module and Arduino.
Maybe an interface like the one used by smartphone alarm clock where you can add rules.
Great! Thanks for sharing!!!
There is already a library for this: WiFiManager!Anyway well done!