How about this as a possible scenario. Lets say you play a map as Spain where your settler starts 6 tiles away (which seems to be as close as you can get a city in range of a Natural Wonder...) from a coastal river hill tile, adjacent mountain with the Great Barrier Reef on your second city ring. There will be a range of resource tiles including salt, fish, wheat and deer.
There are 3-4 other good spots for settling cities all with unique luxuries on river,hill,mountain tiles with access to 2 more natural wonders; (I say 2 and not 3 because I can't see there being more than 3 wonders in reasonable distance to one Civ). These wonders could be King Solomon's Mines, Krakatoa, El Dorado or Fountain of Youth.
I won't say Lake Victoria as I highly believe that that much growth in a 2nd city early would put you quickly in unhappyness unless you had Fountain of Youth. King Solomon's Mines would provide a real boost to hammers which I feel would allow it to become the default military and Wonder city that allows your other cities to focus heavily on science specialists.
These cities would also have a decent amount of jungle tiles in their 2nd and 3rd rings allowing for a lot of science to be generated once universities are reached.
I would tend to put my money on Fountain of Youth as a second or third city site for this simple reason, the GBR will give you 1000 gold immediately which will allow you to plant 2 more cities but that would plunge you immediately into crippling unhappiness but if you can get a spot with the FoY then you should be able to get 4 cities out within the first 20 turns I would assume yeah (you would need to develop luxuries soon though as 3 more cities will eat up most of that 20 happiness). Lets say it takes 3 turns to move a settler to the GBR & on the 4th turn you settle (as the Random Map Generator will not start you on a Wonder). You have 2 production from the city hill tile and extra production from the GBR so you can get 2 scouts out within 6 turns? You scout the other 2 Natural Wonders, and by now you have settlers (paid for by GBR) already moving to settle those 2 wonders (1 being the FoY). The happiness and extra gold allows you to snag 1 more city site so you theoretically have you're 4 cities out by turn 20? I think at this point you probably have about 500 gold left out of the 2000 you found from discovering 3 wonders (1000 from GBR, 500 from FoY, 500 from 3rd Wonder). However I think this gold is best spent on an early worker to start developing those cities & luxuries as fast as possible. Possibly you can hard-build another settler for a 5th city if you can calculate sufficient happiness but that is a risk.
With GBR in the capital I'll assume you can safely get some wonders (Temple of Artemis, Oracle (a must for free policy and GS point) and MoH (only after ToA) for extra gold. Not sure about Great Library (it's still a risk as you have to get it by approximately turn 22 and you already lose 3 turns just getting to your city site with the GBR).
Assuming you can grow fast and stay happy you can get National College quite quickly and you should be able to beat AI to renaissance and get the Leaning Tower and from there quickly beeline to Observatories, Schools & Research Labs...
So, has anyone tried making a map and testing this? It may breach the normal rules to make a map like this but such a start is not impossible in the Random Map Generator (It's extremely unlikely, probably akin to winning the lottery but not impossible)so what happens if you get 3 of the most powerful natural wonders & 4 really poweful starting positions to quickly settle as a Civ like Spain?