The Specialist Economy is normally very good. In this "exception case" of low Happiness, Cottages are really good, too
What's the consensus nowadays? Can a specialist economy like in obsolete's save hold out long term?
I would tend to think that Great People generated from a Specialist Economy are very strong at high levels of difficulty and in general, are a great way to go. I would tend to limit Cottages in the average game, focusing on them mostly in a capital with sufficient Food to run them, then in a few auxilliary Cities.
However, this game appears, at least to me, to be an exception case, since we have such a limitation on the amount of Happiness available to us.
I do admit that we really could use a couple of Farmed Cities in my save, so there is definitely a lot of room to improve upon my approach.
All of that said, for a low-Happiness situation like the one that we have, I would tend to think that building Cottages is the way to go for the early game. I would also contend that in a game where you are able to build and work Cottages early in the game, they will tend to perform strongly in the long-run.
Normally, though, you can't keep your population anywhere close to the Happiness cap and still whip all of the infrastructure that you want to build, so Farms in more Cities than Cottages is a very strong approach. The difference being that we can get to our Happiness cap easily in this game with so many Grassland squares and at least 1 Food Resource per City, making Cottages a strong play--I just went overboard and neglected Specialists too much. But, that mistake is easy enough to correct, with our large Worker force.
Is it the strongest play for this map? That question I will not claim to be knowledge enough to answer. But, compared to most maps, I think that I can very fairly claim that going for mass-Cottages on this map is a lot stronger than it normally is at this difficulty level.
Great Scientist--Go for Philosophy (without Taoism)?
Rather than building an Academy, it would be fair play to Lightbulb Philosophy if we continue to play from my game. We are Spiritual, so there would be no Anarchy hit to switch into Pacifism--meaning that we would NOT have to wait for a Golden Age to do so.
Since Frederick and I have spread Hinduism around to most of our Cities, we could either focus on building the remaining Missionaries using a Monastery or could delay the switch into Pacifism until we have used Organized Religion to build or whip out sufficient Missionaries to spread Hinduism to all of our Cities (which we will want for the Happiness bonus, even if we don't run Specialists in those additional Cities).
But, by Lightbulbing Philosophy, the goal would be to sooner rather than later switch into Pacifism (within the next 20 turns, preferably sooner). Each City has at least 1 Food Resource, meaning that most Cities could get away with hiring 3 Specialists, even without needing to lay down Farms--you might shrink the Foodboxes 1 Food per turn this way for Cities with only a 5-Food Food Resource, while working Grassland Cottages with the excess citizens, but it would be a great way to leverage our low Happiness cap while still growing some Cottages.
The timing of switching from Organized Religion to Pacifism would be up to you--I would say that if you really want to whip a building, try and do so before you switch--which may mean waiting for a number of turns before your Sacrificial Altar/Market/whatever can be whipped. You'll use up less population points or will at least generate more Hammers from each population point whipped in a City with Hinduism when running Organized Religion.
After making the switch to Pacifism and hiring Specialists wherever possible, I would suggest not whipping for a while--which means that you could even switch into Caste System if you really wanted to do so, to better concentrate on hiring purely Scientists or purely Merchants in a few Cities.
This way, you'd get the best of both worlds--Cottages and Specialists--leveraging the large number of Cities to get a lot of both running.
Still plan to make at least 1 and probably as many as 3 Long-term Great People Farms
I would still recommend that you convert at a MINIMUM one City into purely Farms (not the capital, though), and preferably 2 such Cities (maybe even 3 of them). That way, you'll have at least one City in which you can build the National Epic, while having a second or third auxilliary Great Person Farm to be used later on in the game.
Wonders? Heroic Epic? What to do with Rome
I wasn't planning on chasing many more Wonders for a long time, so I had planned to make Rome our Heroic Epic City and thus settled a Great General there. You can do whatever you want--Rome would also be a great spot to pump out Wonders--but I don't think that we'll have enough of a tech lead to be building World Wonders anytime soon.
Astronomy for Happiness from Resource Trades?
Ideally, we'll get ourselves positioned into learning Astronomy, so that we can open up a chance for trading for overseas Happiness Resources.
Frederick has already learned Metal Casting and is on his way to Machinery--we could aim to use Espionage to steal them, which would help along the Astronomy line.
Unfortunately, it is a bit too late to Lightbulb a lot of the Astronomy line, since I have already opened up Philosophy for Great Scientist Lightbulbing and we'll soon open up Paper for Great Scientist Lightbulbing by learning Civil Service, but a combined effort of Cottages + Specialists should allow us to self-tech to Astronomy within a reasonable timeframe (just not nearly as fast as if we'd used a Lightbulb-targeted approach, where Great Scientists were instead used on techs like Compass, Machinery, Optics, and Astronomy). Oh well, Civil Service when you've actually been maturing some Cottages is a good tech to get, too.
And, I think that if we use the Great Scientist on Philosophy and do run Pacifism with a number of Specialists, we'll still get a Great Scientist for an Academy in the capital and we'll get it a pretty quickly, thanks to Pacifism's doubled Great Person generation rate.
Temporary Safety from Frederick
Frederick is indeed one of the AIs that will NOT attack us when he is Pleased with us, so we can safely ignore him as a potential military threat for now--and even if relations do sour over time due to failed Spies or border tensions, causing him to consider declaring war, we at least have both Axemen and Jaguars in our border Cities.
Since Frederick is our only source of Foreign Trade Routes at the moment, I would tend to remain at Peace with him during this turnset.
That said, a warmonger, if they are very successful, could gain a lot, too--a Holy Shrine, The Temple of Artemis, and a lot of Gold from capturing Cities. But, if your war stalls and isn't very successful, then you'll have thrown away a lot of Hammers that could have been switched from Mines into Specialists, and you'll have given up on your additional Trade Route income, so I'd say that if you choose to go to war, go full-out war by stealing Construction instead of Metal Casting from Frederick, working Mines, pumping a ton of units, and commmitting nearly every City to the war effort.
(...you could call out your own save as interesting...)
(1 point): obsolete (strong save, but Frederick is at least something of an obstacle here) 
(2 points): drlake (built both Pyramids and Great Library, but not a lot of infrastructure)
(3 points): Wafflecakes (most challenging 
