Cusco
I have never had a problem going overhead Duxford (unless they have a display) which is unlikely at this time of year, but of course check the NOTAMs first.
Lakenheath dont speak English, so I have some symphathy. The first time I flew in the States it took me two days to work out what they were saying.
As I said in my first post, just go direct. I fail to understand why people want to make VFR flying so complicated. Draw a line A to B if there is any class D in the way ask for a clearance, but have a plan to route around. By all means avoid overheads but that should very much depends on your height and keeping your ears open and listening what is going on. The radio is your friend.
Now I agree if you are not using a GPS, are practising your VOR tracking skills or mark 1 eyeball, pencil and paper, straight lines are not going to work, but I guess you will know that anyway.