I like the Caravelle 12s (NOT the 10B, not enough range) but they're frankly not fast enough for my taste. I mean, when you're flying passengers 2500 miles, even 50 knots makes a huge difference. So I decided I'm going with the fastest planes I can find. When you do longhauls, speed and range more than anything are paramount.
So my conclusion is, given the same number of seats (or comparable) and the same range, spend the extra 3 million or whatever and go wit that plane that goes 50kts faster. That 50kts, while insignificant, is difference between 4 and 5 longhauls.
Jumbos frankly suck. They take too long to build and they have way too many seats for my taste. I think the biggest plane I'm going with is the A300, and at 336 seats, even that's a little too big. For the price of a jumbo, I can get a concorde and another plane in less than half the time. And with the concorde comes a certain prestige factor, a 747-200, not so much. 707's are excellent for those ultra-longhauls I think but the last of them go out of production in 1983 unfortunately. So now I have to find a replacement or get a jumbo.