If range is the concern, just watch your speed. I drive about 65 on the highway and consistently beat the rated range estimates in my SR+. Typical advice is to always get the longest range you can afford. Remember you can still order the RWD LR off menu.
I’m fine with my SR+. On a 500 mile trip, I’d make two charging stops. I like the opportunity to stretch my legs anyway. If I need to get somewhere fast, I fly. That’s my personal philosophy and if you’re very sensitive to the overall trip time you should definitely lean towards the LR. If you’re willing to take your time and you are not doing much beyond 500 miles each way in relatively warm weather, you can probably save your money. Keep in mind that climate control usage impacts range also (particularly heat but also AC - just using the fans uses almost nothing).