I train to stay in shape and to make my body look proportiinate to my body type. Im 5'8 and weigh 168lbs. I wouldnt mind gaining some more weight to, lets say, 180lbs. But I think i would look way too big for someone my height.
What I recommend is, do what feels good and natural to you. if you want to be big then get big, if you want an athlete type body then train to gain muscle but look lean and athletic. And remember, bodybuilding is an ilusion, the leaner you are, the bigger you muscles look like.
Also, I think everything starts with the diet. If you follow a good workout that targets every single muscle in your body, and eat the calories necessary to gain size, you will get bigger...or you can just eat the calories required to maintain and stay lean and ripped.
If you want a good workout, I suggest you try the workouts provided right here on realjock. The Muscle building workout is fantastic and it game me amazing results.
Anyways, good luck with your journey in training. and Have fun with it!!