Generally, a space victory is pretty straight forward if you get a good enough economy (particularly CE) to...
1. Get Liberalism
2. Get Physics
3. Get Communism
4. Get Fusion (all first)
The best way to do this in the early game is to get cities early on (a bit of a REX), cottage them up, and see if Monarchy for hereditary rule is necessary. If you have gold and ivory per se, then you can probably get away from it for a while and trade CoL or a popped philosophy for it. I don't do well with early wars (as far as the long haul for speedy spaceships) but they can be very beneficial. If you do have rivery land that is cottagable, I'd recommend scrambling for it (to get fast tech rate) and start your first war with catas/maces if you deem necessary that you need more land (maces are a big jump and AI's are slow to get feudalism in BtS). Basically, you want a decent chunk of land and cottage it early so that the liberalism (free speech) and printing press duo is the most powerful.
About 3 Golden Ages come in handy during the game. But for GP its useful to:
1. Get an academy with civil service first (Great scientist)
Or: start an early Golden Age, hopefully switch to bureaucracy for free, and pop philosophy with the next great scientist born during/slightly after GA (using the douple GP points that a GA provides).
2. Start a golden age when you get liberalism or democracy to make the switch to universal suffrage/emancipation or free speech/free religion for free (sometimes both in 1 golden age). Often you can backtrack after getting civil service to get the artist from Music to use. Or you could use liberalism to get economics and add the great merchant + free market civic
3. Use the communism/physics/engineer from physics/communism/ and fusion for a late game golden age. Often you can go ahead and burn the physics great scientist because there is lots of time to easily get 2-3 other great scientists born regularly.
I think a late game tech route like this is good (looking at the techs for parts and not the techs leading to them)
->Industrialism (get aluminum and will have coal plants/factories/levees set up)->Rocketry->Superconductors (labs and expensive thrusters)->Fiber Optics(cockpit? quick build and #3 production city can build)->Fusion(engines 1 and 2)->Satellites(#3 production city can get docking bay and cockpit by the life support)->Composites(casings all around)->Genetics(#1 or #2 gets stasis chamber, depends on how things work out)->Ecology (speedy life support in #1 or #2).
By the Genetics/Ecology flexibility: If you assign the #2 city to the stasis chamber and it won't finish by the time #1 gets the life support, you'll have wasted time. If you get the stasis chamber in your #1 and get the life support in the #2, you might save some time if there is a wide gap between how high their production is. If the two cities have close production, it doesn't really matter.
The late golden age speeds up the satellite/composties/etc route to finish strong. AI's don't like to tech trade in BtS so its difficult to trade for medicine and combustion (for public transport and enviormentalism), so you might have to back-track. I'd recommend right before/after superconductors (the labs/factories/coal plants add up by then to get unhealthiness).
Personally, I think that Robotics is a bit of a dead end in BtS, since the space elevator doesn't really add that much. Production in the late game is not a problem, and you only need about 5-7 cities to work the parts the best. I'd leave things as towns until the very end (genetics) and workshop up your 1 and 2 production cities for the final punch into the end: workshopping/farming other cities don't really matter (farming helps beef up your score for GOTM's/WOTM's/BOTM's but otherwise is pointless).
That's the way I see my games work out (not a deity player). I'm a CE player, and a CE is best for an early spaceship, while a SE produces later but more thorough dates. Someone mentioned obsolete, and he runs a variant of the SE with a wonder-focus. But personally I think he wins his dates pretty late, BUT because he wages wars effectively he dominates the game more. SE's that go for space generally bully out the competition IMO, while CE are more streamline and speedier for the finish date. Now it would be best to let DaveMcW explain his stratedgy and listen to him more than me.