Well, it looks like you just like to watch trains run, but you can surely do that with a lot less cost by making your loops much smaller. In addition, it seems like you are OK with lifting the current running trains off the track and placing the other trains you wish to watch "run" on the track since you have no provision for storage on the boards.
Before you actually build this, I highly recommend 2 activities. First, and probably best, visit some already constructed layouts and think about what you like and what you don't like about each. In addition, ask the modeler what he or she did differently on earlier layouts and what would they do differently if they were to start again. Second, read some books and/or articles and/or forum posts about railroad operation (both real and model), about track planning, and about scenery construction. There are many good ideas freely given, but some info has to be purchased, even if 2nd hand.
You have a lot of available space; plan well before you build something poorly designed and become so frustrated or bored that you leave the hobby.