We did a Round the World trip. We were going to the UK anyway and it turned out a round the world flight was cheaper than a Oz-UK return. Saved forever for it too.

We had 3 days Hong Kong. OK, but wouldn't go back
12 days UK including a few days in the Lakes district. Wish we'd had more time in the Lakes, it's so beautiful, but we were catching up with rellies the rest of the time.
5 days New York. Could have spent a couple of weeks there. Would definately return. Saw all the sights, ate at great restaurants, saw a Broadway show. Amazing!
3 days Las Vegas. Meh - it's more DH's thing. We did a chopper ride out to the Grand Canyon and saw Tom Jones. It was fun, but really hot and not my kind of fun
5 days Fiji. Fiji is devine! Loved it and would love to return. We stayed at Lomani resort which is adults only, though next door to a family resort. We mostly slept cos we were exhausted from travelling. We'd move from the bed to the sunbed to the hammock...it's a hard life We'd wanted to go to Tokoriki, which Lulu mentioned above, but that was out of our budget.

If I could do it again, I'd go to Italy. Otherwise, the South Pacific is a gorgeous part of the world. Go island hopping in Fiji or Vanuatu.