Agreed, LHR makes no sense to me. I never know where I am or how to get where I'm going. The only place that comes close is Japan's NRT, but that's only a maze in the 4th floor shopping area.
LHR (except T5, and possibly the new T2 but that only opened this week) is like one of these intelligence testing devices for mice, but for people. You just have to follow the signs and hope. I find that FRA and ZRH are pretty bad that way too, at least for transit passengers, and BRU was managing to hide where the gates were at all earlier this year. (Past the bar and hidden behind some large advertising stands promoting an anonymous sports-car that were also covering up the signs saying where the gates were; yeah, hiding the absolute #1 thing that people want in an airport is idiotic.) And please don't route me via LIN. I'll be good, I promise.
In the US, the places to really avoid are JFK and LAX. Both are horrible places to change planes (especially between terminals). ATL, DTW, MSP, ORD, IAD and SFO are all much better. (MEM is OK, but a bit twisty, and I hate BOS for other reasons that aren't the airport's fault. I've yet to change planes elsewhere in the US.)
Don't know NRT well enough to comment.