KJV is great and beautiful but anyone who thinks they are fully understanding scripture reading that and only that is lying to themselves. English changed too much. It's hard enough with the ESV. I agree with your supplementing the ESV with the NLT and then going back to the source languages as necessary. I also find it useful to read scripture in Latin and Japanese from time to time since I know these languages but trying to understand a verse in these languages forces me to actually understand the verse as I can't confuse native level parsing of the vocabulary and grammar with true comprehension of the material.