I don't know how big your yard is, but I would start small, with the gravel, meaning, just big enough for the seating at first--the point being, you can always expand, but you will never remove the gravel once you've got it in (I'm making assumptions about what you will or won't do in the future based on human nature, the nature of gravel removal, and your post!). Also, will be an issue for the next (owner?)--if you will be responsible for future sale of the property, then that is one reason to avoid some forms of home improvement that may be seen as drawbacks. If you are the least bit inclined to "gardening" and to enjoy a bit of greenery, you might be able to plan and install some pockets of groundcover for the same price as covering everything with gravel--it is possible to build up soil areas without a lot of digging and leveling, particularly for planting one of the tough groundcovers (not for growing tea roses right away!). There would be some upkeep to establish the plantings but again, you could start small-- an area 3x3 or 4x4. You might approach your yard by mapping out quadrants or areas and tackle one or 2 , but leave the rest bare until you phase in the whole plan. The return would be that you would not be trying to establish a lawn from scratch under poor conditions but you would have some green space. You haven't said whether you have any trees in your yard or overhanging your yard--leaves, cones, acorns, maple seeds-- but that is an issue for pea gravel--you don't want a lot of gravel if there is going to be a lot of organic debris falling on it, requiring constant raking and upkeep.

Pea gravel just around the foundation is a dumb idea. It will make the ground around the house more porous,and water will drain to those areas, rather than away. So water drains into the porous soil you've produced, but can't drain down or out because there is heavier, less free draining soil under and round it. You are creating a reservoir of water to seep into your house. But if you have a way for water to drain through the pea gravel and soil and out away from the house, that would be good. In most cases, the best thing is to grade the soil surface away from the foundation, without changing soil consistancy, so that water drains away from the house naturally. (Grading the soil surface away from the house means the soil is higher at the foundation and lower as it goes away from the house.)

Doesn't seem like it's necessary for any more people to cast a vote against pea gravel as a walking surface, but I will chime in with complete agreement that it is one of the best ways to wrongly use a material. Just looking at the slate chips has me casting a vote against it, too. It will be a tiny bit better than pea gravel, but far inferior to other materials. The key to getting a good walking surface of granular material is that, a) none of the materials are larger than about 1/2" to 5/8"; b.) in addition to the largest sizes, there are all sizes smaller all the way down to sand and dust; c.) the material shape is angular, not rounded like pea gravel. (The slate chips fulfill only one of these criteria.) There are many crushed rock materials that work well and they vary with the different regions. One just needs to visit the yards where such things are sold and see what's available. Another consideration if it will be used during the daytime is that darker materials are not as glaring in the sun. (This is important to many people.) As one example though it is hard to find, crushed brick is about as nice as it gets. It's dark, pretty colored and packs down hard. Cinders, if not too large, is good too. In the end, a good surface should be almost hard enough to bounce a basketball on.

Thanks everyone for the helpful input! I was leaning to not using the fabric, now I feel more confident in my decision. Yes, I think for the gravel pathway surface between the pavers and the planter boxes, where it will see more foot traffic, I'm looking for a very hard, compacted surface made up smooth pea gravel mixed with some fines and compacted into either drain gravel or base rock. Our local nursery has this surface, and it looks like pea gravel, maybe mixed with blue fines, compacted into road base. Towards the dry garden, I agree with either bigger gravel but I definitely thought it'd be looser. I have been thinking about what gravel material layers to use for back garden and now the front pathway for about a year! Pro landscapers tell me Decomposed Granite is what I want, but it will carry into house and scuff up floors, and does not drain well, etc. So thats why I'm thinking blue pea gravel as its aligned to our aesthetic wont track in as easily and scuff. I also want a hard surface that drains well and does not pool water, hence me wanting to use drain rock under pea gravel. it feels like DG would stick to your shoes when wet and track and pea gravel wont as its not sandy like that DG. I think Ill do a square foot test - gravel into base rock, or gravel and fines into drain gravel. As for the raw clay soil prep for plants, yes I totally agree with needing a wider hole and or mound, especially in hard clay. The way I usually plant in ground into our hard clay, is dig a hole 3 times bigger than potted plant, then fill the whole 1/3 with 50/50 mix of clay soil and cactus/succulent mix form Hardware Store ( amended mix) . then fill the rest with 100% cactus/succulent mix, mulch on top and superficial pea gravel for cover. Some quick screengrab examples and my updated layers plan