It doesn't look like the semi-peaceful builder approach is going to net us many wonders, but the question is about when we go after the foreign ones. Is it near constant war, or is a builder phase followed by a hunt for the missing wonders, using more modern weaponry?
I think this is right. When we discussed the military option quite early on I think we came to the conclusion that, given we're looking at islands rather than a single continent, and given the game speed, an all-out military campaign was a non-starter. So I think we thought we'd try to tech ahead as fast as we could, build
some Wonders ourselves, get a serious military advantage and then take the Wonders we hadn't built? As far as I knew we were still working to that

I agree it's a bit suck-it-and-see as far as plans go

but on the other hand, if we don't think an all-out military campaign is viable and since we know we can't build all the Wonders ourselves, then I'm not sure what other options there are unless we've changed our minds about the all-out military strategy?
If we're still doing the hybrid approach, then I think it just comes down to how fast we build those 4 extra cities and, as AgedOne is saying, how we handle the impact on the economy (especially if we decide to keep Shaka's other two cities. That's a
lot of extra cities at this stage).
I agree that building Wonders willy nilly doesn't make sense. But if we're all agreed we build Marble and Stone Cities then we're obviously intending to build a few. I think there are three that make sense right now in terms of the hybrid approach of early rex/tech and later military:
- Shwedagon for the early shrine and later priests. Plus it's incredibly quick to build - around 7 turns with gold/organised religion I think.
- Parthenon for the huge GP boost.
- G Lib for the tech boost.
If we get one or two AIs ahead of the pack on techs, they can build the wonders we don't want ourselves. Since it is only 1 or 2 AI's building the wonders, we won't need to capture too many cities to get them. Then we simply need a victory condition to end the game. Could be culture, could be domination if we've killed a few AI's along the way.
This seems very reasonable. Until we have a bit more data on who is out there, though, it's quite difficult to know who to nurture. There's an industrial nutter with stone out there, we know that

It also probably knocks out further military action in the very immediate future - no point in ensuring that our new best friends are on the other side of the world ...