If you are looking to put on mass I would do your flat bench with resistance bands. You will get greet development using any of the exercises on the poll. the problem is how is your chest shaped. The key is not always to go heavy to put mass on. The overall key is to get resistance all the way through the rep. When you push the weight up pause at the top. The bands will push against you requiering you to hold more weight at the top of the lift, I do a 3 to 4 count before I bring the weight down. If you want to be creative you can set up dumbell presses at the cross over machine, If your gym has those leather ankle straps put them at the bottom on each side. Put the leater collars on your wrists. The on the stack put the pins at 20 lbs to start. Now do your presses with the dumbells. You will have the stack going against you each rep. Stay with the same dumbell weight but go up on the stack each set. Your goal is to get the stack up to the same weight as your dumbells. So if the dumbells are 50lds and the stack is 50lbs you are pushing 100lbs but the resistance against you is equal. This is by far the best chest exersize you will ever do. For the record I have my PT cert from NASAM. Good luck with the development.