I'm currently running a 10 year old above ground fortress with only mining tunnels being underground. There were several above ground forts before this one that were all abandoned for various failures i have since learned from. Since building ANYTHING above ground is akin to a mini megaproject i set the pop cap to 30 (for fps reasons), build a small(20x20 tiles) log fort in a corner and i roleplay those 30 to be a construction team sent ahead to ready the site for actual colonists. When the city is finished pop cap will be released and everyone will instantly fit into their predesignated house and workplace.
That's the theory anyway.
In practice of those 30 there were 11 married couples plus 2 couples from starting seven which married later. 10 years later i have 90 population of which
60 are children. Needless to say it's a haven for snatchers. Originally i only planned to wall the starting mini fort to stop snatchers but that did not work so i spent at least 2 years building a wall encircling (it's a square actually) the future settlement. Now my entrance is small and i only need to patrol that so only about 1% of snatcher make it. A note for every future above ground fortress overseer: make a plan upfront on how to deal with snatchers, you won't have the safety of the mountain so you need to make lots of patrol routes and/or lots of walls.
With my workers being all over the place i started to dread caravan arrival because they are very often followed by ambushes and without the safety of the mountain i more than a couple of woodcutters are in dangers. This contributed to the decision to build a proper wall.
My original plan was to use a single 4-6 squad of marksdwarfs ex-hunters to deal with ambushes (every one of them was left with hunting labor on until they reached at least adept level), however the babies pushed my population above 80 which invited sieges. Luckily one of my starting 7 was a proficient axedwarf/proficient teacher and he spends the whole time training with an immigrant grand master axedwarf. They are the only part of the fort which are full time soldiers (with only 30 adults i need every pair of hands available for construction). They are now legendary and can deal with an infinite number of sieges by themselves (barring a lucky lasher hit).
I have zero agriculture, having no problem sustaining myself on hunting, fishing, plant collecting and trading. All alcohol except for an occasional import is made from above ground plants. My main export is iron weapons/equipment, i buy all wool and cloth for caravans for the never satiated clothing industry (babies are born naked so when they grow to be a child they require a full cloth set, with 60 children... let us just say that my dabbling clothier quickly reached legendary from the 24/7 work he has been doing), although i like to make every type of clothing you really only need shoes/socks for feet, trousers for legs and anything for torso to make them not naked.
I planned to move the construction team from mini fort in a city once it has been completed 100% but then i realized that married couples+children share rooms so even though i had 90 dwarfs i only needed about 17-18 homes for all of them so now they are living in an unfinished city while the old log fort serves as a warehouse and a workshop complex for every workshop which did not have a structure built for it in the city proper.
The embark site is 5x5 near perfect flat plain with a lake, heavily forested (it better be for all the construction i'm doing). The lake helped me primarily to pierce aquifers because for some reason the embark square that contains lake doesn't have one. The temperature is warm which made me feel ok with turning off temperature in .ini file because at you do not lose any features (too warm for pools to freeze too cold for evaporation). Because of all the clothing i made for 90 dwarves and all iron gear for soldiers wealth while small bloated enough for me to be granted a barony and next year a county.
Every and i mean every building is built exclusively from blocks with stone blocks for walls and wood blocks for roof and floor (i treat wood blocks as planks), with new update giving you 4 blocks per stone job the main time sink is making all the wood blocks, eventually i ran into situation where i chopped >90% of the trees on map so now i am waiting for nature to hurry up and give me my construction materials.
Starting seven were (proficient unless noted otherwise): armorsmith/weaponsmith, carpenter/bowyer, mason/stonecrafter, axedwarf/teacher (for future army projects), novice ambusher/skilled marksdwarf/leatherworker and architect/some combination of judge of intent and appraiser that i don't remember anymore. Nothing special about this embark strat nor in any way specialized for above ground fortresses aside from the lack of miners and a single hunter.
Currently i have completed a tavern (2-story building, dining room down, drinking room up), hospital, barracks, cloth manufactory (loom and dyer's shop included), soap manufactory, distillery, several houses and as you can see lots and lots of roads. The unfinished walls on the right is a future tomb complex (which is one of the rare things that will be built underground), the unfinished flooring on the left is dried up murky pool being walled in, beneath those roads are several ex murky pools all pumped out and replaced with rock walls, in times like these i wish DF would have soil blocks like minecraft so i could fill murky pools more easily. Construction is very slow because i don't have the guts to activate masonry and carpentry on all 31 dwarfs. Overall the town is still in the early stages with lots of workshops and stockpiles being left out in the open. In about 5 years 20 children will grow to teens so things will speed up from then i hope.