I am taking a trip soon to London and will possibly be adding a couple days in Paris. It's been a hot minute (few years) since visiting the UK and would like to solicit some timely advice and tips. One thing that comes to mind: How important is it to carry cash? Would I need to pay London and Paris street vendors or any shops with cash or will a card with no exchange fees suffice? While we will of course be visiting some tourist attractions like museums, most of our time will be taken up with book stores, record shops, food and coffee shops.

My wife and I (from the U.S.) are going on vacation and as part of a larger itinerary have scheduled a week in Northern Ireland, based in Belfast. We'll spend the first couple of days decompressing and exploring the city, but besides that I'm wondering what would be worth doing there during that time. I've been focusing on the other parts of our itinerary and have only very limited knowledge of that area and its attractions. We plan on renting a car for a day or two to get out of the city but otherwise will be relying on public transit. Thanks in advance for any recommendations or advice!