Those SRW prices are typical. I don't think you will find experienced installers that will do a multi-tiered wall for less. You should make very sure that the installer has done multi-tierd walls because there are additional concerns. I gather from your posts that this is a fill slope that is being retained. If that is the case, compaction of ALL of the fill under the base material for the upper walls is very important. That is a lot more work than a standard installation. Another price influencing factor is that you have many more linear feet of base preparation for multiple tiers than you would for a single 10' wall. The difficult thing is both the set up and compaction of the base material and the precise setting of the bottom course of blocks. After that it is pretty simple, although labor intensive. A long low wall, or series of low walls adding up to 1,700 FF should be expected to be a lot more money to do than a single high wall of equal FF. One of the least expensive walls in areas that boulders are not far away, is a rip-rap or boulder wall. These can be done very nicely when there are well experienced installers who do this a lot.Otherwise, they can be pretty primative. Without seeing your site, it is hard to know. But, in situations where multi-tiered walls are used, it is not uncommon that the bottom tier is not viewed from the interior or approach to the property. When that is the case, aesthetics of that bottom tier is often a lower value than budget an practicality. If that is the case in your situation, you might consider having a boulder wall as the bottom tier and then going with a more aesthetic materiel for the tiers that are more visible. Keep in mind that the boulder wall is thick (front to back) which limits how close you can plant to it should that be an issue. That is one way to reduce costs.

Kristen- I see a Screened Porch on the deck above to provide a dry area below. Seems like a perfect fit for your nice home...and you did say that this could be a multi-phase project :) I would add lattice work around the posts underneath and gravel as a base for storage accessed by a lattice framed door. Electronics could go against house midway back. Can't tell from the photos how much headroom you will having after excavation down to the footers. You may indeed have enough height for a use an enclosed room. Doug

helshar, The best thing to plant for erosion is GRASS, the bigger the better. Bamboo, ornamental grasses, not regular lawn grass. Grasses. They use it on horrible steep slopes here in SC all the time.

The small tree is a tree FORM. Make it out of a large shrub so it's roots will not be too extensive. What is the brick cut-out? It looks like an unfinished construction. I figured it was temporary and would be "healed." Next step for you is to create a base plan where all the features (house/wall/deck/tree trunks/shed/fence, etc) are located accurately. Then draw bed lines. Begin placing plants. Use appropriately sized circles for larger plants and outlines for plant groupings. If you make multiple copies of the base plan and scratch out your ideas until they are refined. You've got to convert ideas in picture, refining as you go, to a PLAN in order to know that things fit, are properly located and so you can calculate quantities. Once the plan is finished, you can create a plant list based on it. And then go shopping. If you're doing irrigation, it should be installed after large trees (if any) are put in place, and before all the other plants. If no irrigation, Fall is the better time to plant IMO as roots get more time to develop before hot weather arrives.