Hi Karen,
I've run Edinburgh 4 times in the last five years, and if this is going to be your first marathon I'd highly reccomend it, it starts on Regent Road and first 4 mile are down hill /flat and then you follow the coast road though several villages up until the 18 mile mark when you run through the ground of Gorsford House and then turn back and finish at Mussellburgh race course.The spectators can be sparse at times and pick up at various spot along the course, usually in the villages, and at the finish, The weather can play a major part, the first 3 times I ran it the weather was clear blue skys 25C, (not ideal running weather) but the spectators were out in droves. and the last time I did iit, (2011) the weather was horrendous, driving rain & Very Very Very windy.
I know a few club member have run Amsterdam
hope this helps,
Michael