I think you'll find yourself wishing you got the 128GB model at the very least. While its true you can store your documents online only with OneDrive, you also have to consider patches, updates, and upgrades, such as windows 10. Add in space that your apps will take, and its not a stretch to think that that you'll be running out of space fairly quickly.
I think you need to figure out your max space needs now, its growth, and then pick a configuration. Trying to shoe horn everything in now into a rather small storage configuration will only result in frustration.