Originally Posted by
IADCAflyer
I don't know anything about LIN or MXP so I cant say if one airport is seen as being more of a hassle to negotiate versus the other. MXP is certainly -the- major airport for the Milan area while LIN is significantly smaller.
LIN = DCA, much closer to the city (~20 min taxi) but with only regional and European flights
MXP = IAD, larger airport outside the city (~50 min train) that has all intercontinental service in addition to European and regional
If you're in the city then LIN is easier, at the end of the day there really isn't much difference between LIN-MAD-PHL and LIN-LHR-PHL. If I were the OP I'd probably go MAD, slightly shorter and arguably easier connection than LHR, and it gets into PHL almost an hour earlier.