My entryway usually consists of three hallways: the safe one, which is long, full of war dogs, and leads to the trade depot; the one for sieges, which also leads to the trade depot, but is shorter, traverses over a long pit trap, and has~30 tiles of cage trap at the far end to catch runners or big things; and a very short hallway, which is an artifact-baited building destroyer trap. All of the entryways have bridges to close them off if I need to route traffic.
Since my first year is largely devoted to building my entryway, I usually have a big ~10x20 room near the trade depot for a big "get it all indoors" stockpile, a small dining room, a couple beds, and assorted early game workshops.
Once I'm secure, I try to discover the first cavern, so I can plan my living quarters level. This is usually a couple levels below the bottom of my pit trap, unless the cavern gets in the way. My living quarters level has 3-tile-wide main corridors dividing it into 23x23 blocks. One of these big blocks closest to the stairwell holds a 21x21 hospital, and another holds my 21x21 main dining room. All the other 23x23 big blocks I carve into 9 7x7 dwelling-blocks, each of which I make into either a 5x5 noble room (with 4 pillars inside), or 4 2x2 bedrooms. I usually reserve a dwelling-block near the hospital for a well. I have different well designs depending on if I'm getting water from above or below - if from above, I only need a 2x5 space and so the well can have two bedrooms next to it; but if from below, I need the whole 5x5 space.
I usually start with just the four big blocks around the central staircase, and expand out only when I need to.
I set up a big farm block on the level below a big flat space of ground, so I have room to dig down and create surface-plant "greenhouses." Depending on how much room I have, my farming-related workshops will either be on the same level as my farms, or on the level below, connected by a staircase-hallway so that the dorfs don't have to go alll the way back to the central staircase.
I set up my magma forges a couple levels below the living quarters, so that I don't have to thread magma supply up through the living level. If I have sand, I'll put a couple magma glassworks up near (but not inside) the farming block, and let a hauler fill it from a minecart.