well...IMO chamber 17 is one of the hardest to get least steps. This is how i did it. I'll try and benchmark it using steps for each step.
-First get companion cube. Then jump up to the first portal-able wall...Place blue portal. (the least i got is 34 steps to here)
-Now hold the companion cube infront of you as you go down the hallway. Jump the steps. Go back the parallel hallway. *watch out for plasma balls* Jump steps in the best you see fit for less steps. (around 80 steps as i enter the room with the first plasma catcher)
-This next part takes time, patience, and LUCK...and a bit of logic. Jump down to the middle of room. (86 steps) Place orange portal on protruding wall. Deflect incoming plasma ball into the room without the buttons. In time it will be caught by the plasma catcher in there. (still 86 steps)
-Standing in the same spot you must deflect another plasma ball into the back of the room with the buttons...and into the catcher behind the 2 doors. This one will need to be worked with, as finding the right angles is just up to you. Until you finally get it you still should have (86 step...give a couple if you must reoriant yourself to get it)
-Now go to the last lift with companion cube. (97 steps) It should still be down. Stand on it and shoot a new orange portal on the angled wall across from the plasma ball catcher. Be sure and hold on to your companion cube, as a portal will come out and automatically be deflected into the catcher. Thus raising the lift you are on. Jump to the ledge. And try to do the rest with least steps. (you can use 53 more steps for a total of 150 steps for gold)
I have done it in 147 steps. Lemme know if you get it.