What should guests give Richie McCaw and Gemma Flynn for their wedding?

What do you get the couple who have everything? Gemma Flynn and Richie McCaw when he received the Order of New Zealand, will wed today in Wanaka. Photo / Mark Mitchell.

What do you get the couple who already have everything?

It's a tough choice for the wedding guests of All Blacks great Richie McCaw and hockey star Gemma Flynn, who will walk down the aisle today.

What kind of gift to give New Zealand's golden couple could be tricky.

To start off with as retired All Blacks captain McCaw doesn't need cash - he held a $1 million contract when he was on the field and off it the former flanker pulled in $1.5 million in sponsorship and endorsement deals.

So throwing some money in an envelope into a wishing well at The Olive Grove in Wanaka, where the sporting couple's secret ceremony is set to take place, might be a tad awkward.

As brand ambassador for Mercedes-Benz the Kiwi sporting icon's vehicle of choice is the new SUV Mercedes-Benz GLE 350.

He's been the face of Versatile Homes, and there's the small fortune in property McCaw has amassed, seven altogether including a $2.5 million executive family home at a bluechip address in Christchurch which he and Flynn bought last month.

It's unlikely then that harking back to a traditional gift such as an appliance or some crockery will be necessary.

As far as memerships to exclusive clubs go, don't forget McCaw was the youngest person to be made a member of the Order of New Zealand earlier this year when he was 35.

An astute investor, McCaw has shares in the aged-care sector as well as a 10 per cent stake in a Canterbury quarry company, so don't bother with Bonus Bonds or a Lotto ticket.

And then there are the adventure-related gifts.

McCaw is a helicopter pilot so getting the couple a scenic flight or flying lessons would be pointless.

Now that Black Sticks Flynn is into adventure racing it's likely she will have acquired all the kit she needs to battle it out in races such as the one in Golden Bay involving mountain biking, rafting and running that she took part in back in September.

Clothing also needn't be considered as Flynn has that covered. Not only is the 26-year-old able to dazzle in designer dresses at red carpet affairs, she's even sprucing McCaw up in elegant threads.

In November 2014 she bought her beau a $1000 blazer she had specially embroidered with a personal message to commemorate his 100th test as captain.

If all those gift ideas are out then perhaps some unisex baby clothes or toys might be the way to go?