skip the 17-40. There's a couple perspective shots you could do, or more dramatic shots of people and their surroundings, but it's generally a bad idea to shoot portraits of people with wider lenses as it will distort the proportions of their bodies - and if you are shooting photos from the midriff up it will distort faces and make them look odd.
Most people that are shooting headshots and the like will use something 80mm+ on a full frame, which your 50 will work for assuming you are using a crop sensor cam (forgot if you mentioned that). Don't get into the habit of shooting everything f1.8 - there's a place for that for sure, but it's not every shot you take. Even at 1.8 you may cream out your background so much that it's just a colorful blob, and that's not always great.
Experiment with it, shoot a bunch, edit your best shots and then decide how they could be better. Then shoot some more with notes!