Like I said, “sweeping generalities”. I assert that the majority of US accents are rhotic, and the majority of English accents aren’t. Not only that, but the entirety of Irish accents are rhotic.
American tourists often have two things going on: (i) a box-ticking mentality, where there are lots of things they want to see and do; (ii) a desire to one-up other American tourists by getting more ‘authentic’ experiences.
You should play to these. One of the boxes to tick might be ‘bone a local’. So your task is to help them tick this box. The way to play it is to use (ii) – with your mates, start drinking with the tourist group. Start making hints that ‘nobody you know ever comes here’, ‘you just wanted to see what it was like’, and ‘it’s for tourists only’. Then as the evening goes on, suggest a ‘more authentic’ alternative place to go to, then back to your apartment.
Honestly it won’t be that tough. In terms of Yank tourist one-upmanship, “we met these cool Irish guys, and they took us to a really cool pub where the locals go, and then back to their flat. it was great to see how Irish people really live” is gold, and they’ll happily suck whatever you have to offer to get at that gold.