I did the Trans America and some other long tours with the same saddle that came on the Fuji a few years ago. I was pretty happy with it once I adjusted to it. I'd probably do the same with what comes with the bike now. I have done other multi-week or multi-month tours with the saddles that came with my other bikes.
Bottom line... I recommend giving what came with the bike a good chance, slowly building weekly mileage. If necessary try something else, but there isn't any silver bullet.
There are a lot of Brooks fans here, and I tried to get one to work and couldn't. Apparently I'm one of the few. So I also used the stock saddle because it worked fine for me. If you can ride long days in it repeatedly (and you should know this before your tour), it doesn't really matter much who makes it. I met one cyclist who tried the saddle I use and couldn't stand it. It's a very personal choice. Ask ten cyclists and you'll get eleven opinions.
I heard you should avoid padded saddles when cycling in hot weather--something about insulation when not wanted.