Any input on whether it is best to rent a car in advance via a U.S. car rental company, or rent one when we arrive in November? We plan to take the train from London to Edinburgh, and then rent a car for 3 days, returning by train to London. Based on the posts I have seen on Fodor's, it looks like our US drivers license is sufficient. Any other suggestions are welcome and appreciated.

Definitely rent ahead from home. You will usually save between 20% and 40% over walk-up rates in the UK. Plus, then there are usually no drop off fees, etc.

W/ all of my trips, only once was booking locally cheaper. That was when I flew from LHR to EDI on BMI and before landing the cabin crew announced a special promotion. W/ a BMI boarding pass, the Avis counter at EDI would give a large discount. I wasn't needing a car until 3 days later - but Avis said they would honor the promotion. So I cancelled my existing booking and rented from Avis.

But that was a special case - -

Am I right in thinking you mean you'll stay a few days in Edinburgh, then leave & tour other parts of Scotland by car, the go back to Edinburgh to get the train back to London ?

If so, it's better to rent a car for when you leave Edinburgh rather than as soon as you arrive - a car is a liability in the city.

Also, have you thought about flying between London & Edinburgh ?

Oh - hope my post wasn't confusing. I picked up the car 3 days later when leaving Edinburgh. No, you/don't need/want a car IN Edinburgh. I'd pick one up for touring after visiting Edinburgh.

(that is sort of what I assumed you meant - 3 days outside of Edinburgh)

Yes - all you would need is your Stateside license.

Yes, the car is for use outside of Edinburgh.