There's no way in hell am I going tour anywhere whilst driving on the left side of the road............LOL!
It takes an hour or two to get acclimated and a whole lot longer to get comfortable. Touring the the countryside is no problem - just stay focused and make sure the center line is on the same side of the car as the steering wheel. It's the cities with the big roundabouts that freak me out.
I used to have to fly into Sydney, pick up a rental car, turn left out of the Alamo parking lot, get over into the right lane, turn right at an intersection about 3 KM up the street, hang another right a couple of blocks up from that, then turn left into the office parking lot. Simple enough but those two right turns required a physical force of will not end up in the oncoming lanes but after that I was usually OK.
You'd be surprised how fast you get used to it. I drove around Ireland for a few weeks a few years ago and even enjoyed negotiating the many roundabouts. Of course, I should mention Irish roads are a lot more twisty and narrow than your average American roads. And there plenty of stone hedgerows lining the roads so you have to be careful. But overall fairly enjoyable driving. And the Irish drivers were very good.