I think the "introvert"/"extrovert" difference is key here, Iluvcruz. Dh can't help the way he is, anymore than you can help how you are. We're talking about basic personality here. And, of course, though 60 is still "young" in these times, you are both getting older and more set in your ways.
So I think you need to try to respect each other's differences. Not just compromise because you 'have to" - you've done that. I mean really try to understand and respect that the other has different social needs and don't try to nudge each other to be different.
Of course, there still has to be some compromise. Would dh be ok with the trip if you just stayed in one place and didn't do all that flying around (and constantly having to meet/deal with new people, I suppose)? Would he prefer to go someplace where you people have friends or family, so he would feel more comfortable? Would it help if you shortened the trip? Or just planned a cruise, as another poster said?
If none of these ideas are workable, then, I say, yes, go to Australia on your own. Again, maybe cut the trip shorter if you don't want to be away from him too long. And, maybe, get to do some things you wouldn't if her were there. Celebrate your Ruby some other way, either before or after you go, with a lovely dinner in and, perhaps, a good DVD and some wine or something. Make the trip about getting to be totally you and doing things you like to do.