Jaime-
Welcome to Large Scale Central.
There is much experience shown on the LSC site. Here are some considerations from my 14 years in the hobby:
1 - If cost is a consideration, give some thought to aluminum rail – there are numbers of comments on the pro and con. At this point, the major objection was (has been) electrical continuity is diminished. Apparently, a number of readers have cited this is untrue. The cost is over 1/2 of brass or nickel, let alone stainless rail.
2 - Use 332 in any areas whereby you will need to walk on the track - granted, you are elevating it. However, any plants or scenery means maintenance by a human.
3 - Choose a layout location where most people will be able to watch, on their own, the layout. Having it in a portion of the yard that requires a specific approach to see it means there will some viewer conversation and then people will shortly return to where the seating is – and likely food and conversation. Having it in the back of the backyard behind the roses is not going to make it a repeated destination. If you have to take people to “see the train,” you are likely in for a one-time visit by any relatives and friends that are not RR addicted.
4 - Any chance of an "L’ or dog-bone shape means people will not be able to see the layout in its entirety with one glance. Head movement means a change in scene and less chance of boredom - especially from those who absolutely cannot fathom “having toys outside in the wet.”
Good luck - please keep us informed of your adventure
Wendell