Here's a diagram of my setup:
I'm using MQTT to send the sensor data from several NodeMCUs to the Raspberry Pi, storing the data in a MySQL database, and writing a Python server to show both realtime and historical data.
I'll be using Google charts to display the data, and using JavaScript to poll live data from the Raspberry Pi though a JSON API.
I'm still working on this project, but I'd like some feedback. Are there better or easier ways to accomplish this?