As we use British Airways the vast majority of the time, and they’re currently using Heathrow as the airport for the direct Denver flights, it’s our most practical option, love it or not. But it’s usually been OK for us. Flights that have connected thru London Gatwick have been a bigger ordeal, with really long walks down endless corridors, and confusing signage and inconvenient/disorganized security and border control operations.
Biggest pain with Heathrow is that they wait until almost the last moment to announce the actual gate from which your connecting flight departs, then you have to scurry to that gate to make the flight. That, and options for enduring long layovers are decreasing. The Yotel at Heathrow has shut, and we wanted to get a tiny but convenient room to rest there this September, because BA has dropped their mid-afternoon flight to Bologna. Now we have to wait until a nighttime flight, so that means hanging out in plastic chairs in the departure waiting area for a really long layover, until that departure flight many hours after we first arrive.
Would you at least land and connect in the same terminal (maybe Terminal 5?), or do you know right now that you’d have to transfer terminals to catch your connecting flight?