People have argued in the past that the Hursts, Caroline and Charles Bingley, Georgiana Darcy and her companion are enough to constitute a "large party" all by themselves (because we know that Darcy is a hermit who doesn't have any friends besides these, right? ;-). However, when JA wrote "large", I'm convinced she meant large! You raise an interesting point, though, about whether they all travelled together and how it would all work. Maybe Julie can answer that one!

Some more evidence that there were more guests than just the six we know about:

Mr. Gardiner left them soon after breakfast. The fishing scheme had been renewed the day before, and a positive engagement made of his meeting some of the gentlemen at Pemberley by noon. (ch.44)

Leaving out Mr. Hurst (I can't really picture him going fishing, can you?), if that left only Darcy and Bingley, why not say "Darcy and Bingley" instead of "SOME of the gentlemen"? On the other hand, if Mr. Hurst *had* gone fishing, IMO JA would simply have written "THE gentlemen", not "some" of them.

[Darcy] had been some time with Mr. Gardiner, who, with two or three other gentlemen from the house, was engaged by the river. (ch.45)

Darcy and Mr. Gardiner are mentioned by name, so that leaves Bingley and Mr. Hurst. Who might the third gentleman be? In ch.45, only four ladies are mentioned as being present when Elizabeth and Mrs. Gardiner visit Georgiana, but it makes sense to me that a bachelor would have mostly male guests, and I think those male guests would not be present at a morning visit between ladies, anyway. (Also, perhaps some of those gentlemen travelled on horseback rather than by coach?)

Like Carolyn, I'm trying to list the various people in P&P whom JA mentioned only once, and there are quite a few. I'm convinced that JA expected her readers to understand that her characters had a much wider social life than just each other - she just didn't mention all these people because they were not necessary to the plot!