My son in law needs to do the following trip to attend meetings/present lectures at each destination. We would appreciate your guidance.
Travel has to be in economy unfortunately.
Sydney - London Dep 9 Nov
London - Alberg (Denmark) Dep 13 Nov
Alberg - Edinburgh Dep18 Nov
Edinburg - New York Dep 21 Nov
New York - LA Dep 23 Nov
LA - Dunedin Dep 25 Nov
Dunedin - Syd Dep 30 Nov
I appreciate your help, and I know the rules ref gratuity.
This is certainly I complicated routing and I can see why you have asked for help!
I have had a look at the star alliance round the world option and various other options and found them to be very expensive (the star alliance ticket was almost $6000). I would say that the most cost-effective way to book this would be to fly Sydney-US-London-New York-Los Angeles-Sydney on a single ticket, and book Aalborg, Edinburgh and Dunedin as side trips.
It is quite easy to find cheap travel intra-Europe, so you should be able to book London-Aalborg-Edinburgh-London fairly cheaply. In terms of Dunedin, there are no direct flights from the US to Dunedin, so you would have to travel via AKL with Air NZ or via an Australian port. So unless you book with Air NZ, it's probably easier to treat it as a side trip from Sydney.
Let's look at this as 3 "sections", as outlined above.
Section 1: SYD-London-New York-Los Angeles-Sydney
I have found this routing with a few different airlines;
United is AUD$1966. They have fairly direct and well-timed flights, but United long-haul is not a great deal of fun, so I guess your son-in-law would need to consider cost vs comfort.
Qantas is $2978
Delta was around $4000
I was unable to get a quote from the websites of Virgin or Air NZ
I don't think you will find a cheaper price than the United quote. This routing was SYD-xLAX-LHR-EWR-LAX-SYD on the dates you have listed using the multi-city booking tool on the United website.
EDIT: If you're not to keen on United for all the long hHal travel, you could book separately SYD-LAX return via Fiji with Fiji Airways for $1140, then buy LAX-LHR-NY-LAX with a cheap airline, or even LAX-NY on one ticket and NY-LHR return on another. Just be careful that connections are not tight and be wary that there are several different airports in New York. I have not found a combination cheaper than United, but I have got close, so it's just another idea and of course, you could investigate further if you want.
Section 2: London-Aalborg-Edinburgh-London
Only 1 airline (Norweigen Air Shuttle) flies from London to Aalborg and they only fly there 3 times a week - Tues, Thurs, Sun.
A return flight on operating days is €102.60 (AUD147). The days you have listed are not days in which the flight operates however the airline does offer flights on these days via Copenhagen (for around double the price). If he arrives/leaves a day earlier the direct flights are available. I would then book London-Edinburgh and return separately. You can get tickets on easy jet for around £33 oneway (+£9 for 20kg baggage). All up that's around £80 ($135). Just make sure you leave plenty of connection time as connections on both ends will be on separate tickets, so no protection if one flight is delayed etc. Also note that there are different airports in London so be careful of having to change airports. After Edinburgh, perhaps it would be a good idea to fly back to London the night before flying to New York.
Section 3: Sydney-Dunedin-Sydney
This is probably the easiest part to book.
You can book Air New Zealand Sydney-Dunedin return (via WLG or another city) for $446 without baggage or $496 with baggage. (Dep 27 Nov, return 30 Nov)
Alternatively, you can get a cheap Jetstar/Qantas fare to CHC/WLG or AKL and connect to a JQ/AirNZ flight to Dunedin for less than $446 in total. Currently it is possible to book a JQ flight AKL-SYD for $85.80 if booked as part of a return ticket originating in Sydney (this is only a limited sale though). There are plenty of cheap seats AKL-DUD.
All up this would come to AUD$2744 to get to every destination including baggage allowance. I hope this is useful to you and if you need anything clarified feel free to ask!