So our new house is going to have a bit of a slope right behind the house...then it levels off several yards on further back. The problem is that we want to keep several of the mature hardwood trees (for shade). So if we level the entire back of the lot, we'll have to lose every single tree. An in-ground pool (something I cannot talk the family out of) is inevitable within a couple of years of moving in. So, if/when we decide to do the pool, we'll have to cut the bank way back to make room for it. The further back it'll go...the higher the terrain is. So a retaining wall on the back side of the pool apron will have to go up in order to keep the trees...and we can also sow in some grass and have a 'back yard'. Also I'll have to cut a driveway on one side that will lead to my shop that I'll also build to keep my Camaro in. So, comes the question. Stone, RR cross ties, or block? Money does play a key factor. Of course I want the best bang for the buck, but I also want something that will be trouble free, durable, and long lasting. I care more about those things more than I do looks. I feel like we can make the most of whichever material we decide.