Can you recommend a dynamic, concrete, or easy-to-play line against the London System? I hate playing against the London because it allows 800 FIDE rated players to survive for 50+ moves. 

By the way, I play the Grunfeld against d4, the Sicilian Najdorf against e4, and the triangle against most Nf3 systems. I also play the Ruy Lopez and the most mainline e4 lines there are for white. 

So do you have a strong, venomous system that combats the London move order? I looked at 1. d4 Nf6 2. Bf4 c5 which I like for Black, but they can play 2. Nf3 first. Any recommendations? I accept fianchettos and systems where the light squared bishop gets developed.

Thanks in advance!
According to modern theory, playing the QGD as if you were white is the best option.  (That is, of course, just to sell more useless books.)

I play an early Bd6 to challenge this system, but the problem I experience is when they don't trade the bishops.

The logical plan is to play the KID.  The bishop will be "biting on granite."  When the time is right, pushing the e pawn will gain tempos on the Bf4 and Nf3, and since this system mostly develops the Bd3, a fork is possible.
Another popular theory is to exchange on d4 and plan for a minority attack.

None of these seem dangerous, but you can use their development system to expect certain moves.  You know that they won't be attacking with c4 and you know that they will place a knight on f3 (and later on e5.)  An early Bg4 to avoid the bad bishop, and, since they aren't attacking your center, this bishop won't need to be protecting b7.

Also possible is to develop your bishop before establishing the triangle formation. 

These won't prevent long games, but it may provide you with positions that you are more comfortable with.