Too much attention to foreign fields can result in a few tantrums back home. In the Far North last week, Mayor Wayne Brown wrote a truculent column about the attentions John Key had given to the Pacific compared to the Far North. Later, callers to a talkback show grilled the PM about giving aid to Pacific countries when New Zealand itself was hardly rolling in the money.
A supporter of medicinal cannabis castigated him for "enthusiastically" swigging back "a psychoactive substance called kava" despite rejecting bids to allow the use of marijuana for medicinal purposes at home.
They should get their pens ready again - Key is off in a fortnight to Cairns for the Pacific Islands Forum leaders' meeting. He will visit Australia again soon after to meet Prime Minister Kevin Rudd to push for the furtherance of the single economic market goals.
Then he is off to Trinidad and Tobago for the Commonwealth Heads of Government Meeting. A trip to the United States follows the month after.
By choosing to take over the trip that is traditionally left to the Minister of Foreign Affairs, Key is sending a clear indication that he intends to be no less prominent in foreign affairs than Helen Clark was.
On the face of it, it was a "good will" mission.
After a decade of Clark, the leaders must have wondered what they were in for. It didn't take them long to find out. He has a proclivity for what the media call "Clark would never have done that" moments.
There was a "Clark would never have done that" at the lively nature of Key's delegation, complete with hip-hop dancers and former All Blacks. There was another as Key camped up his dance with Miss Niue, and again as he used the word "children" about Fiji and Samoa when commenting on the relative merits of their kava.
"Clark would never have done that," they muttered in Tonga after Key hollered out a joke to them about the King's dog Poobah.
It is true that Clark - a polished performer on the international stage and well aware of the gravitas of her role - would never have done the things Key does.
But the difference is deliberate and, for him, it works. He knows he lacks the grounding to emulate Clark, of whom a foreign affairs mandarin once said - only half-joking - that she was better placed to brief her officials than to be briefed by them. His personality is also starkly different. Key has never been risk-averse, as long as the risk is calculated. The trip proved that. The delegation, which sometimes looked like a circus, did more than simply cement Key's relationships at a leader-to-leader level. The hip-hop dancers proved strong ambassadors at a level Key could never have reached.
But the leaders of the countries he visited will also have learned that after the dancing is over, Key plays as straight a game as Helen Clark did.
Niue's Toke Talagi, in particular, learned not to try to lure Key into a diplomatic game by playing China off against New Zealand in a bid to have aid funding released. Key called his bluff - telling him to go ahead.
Key takes a pragmatic stance on China's incursions with aid money and easy loans into the Pacific. Rather than rail King Canute-like against it, he has instead publicly said China's increasing role is an inevitable consequence of its efforts to gain wider international influence.
Instead of protesting, he has urged China to work with New Zealand. His aim is not only to ensure that aid money is not spent on wasted efforts, but to allow New Zealand to see exactly where it is spent.
However, he has also sent the clear message to those island countries that they deal with China at their own risk, that New Zealand will not step in to bail them out if it goes awry.
Behind doors, Key also tried to shore up support for centring the Pacific forum agenda next month on them and the economic downturn - not Fiji.
The Pacific Islands Forum has often been criticised as being of negligible value, a grouping that talks a lot but does little. Such outcomes are anathema to Key - and so his reconnaissance trip was more about trying to ensure something concrete emerges when the leaders meet in Australia.
What he wants when he flies into Cairns is allies to help staunch talk of allowing Fiji to rejoin the forum. What he wants when he flies out of Cairns is to be carrying a communique filled with concrete proposals on measures to help the Pacific Islands in the recession.
So as soon as Key returned from his trip, Foreign Minister Murray McCully went on his own - to Kiribati and Tuvalu, as well as follow-up visits to Tonga and Samoa.
Duncan Kerr, the Australian Parliamentary Secretary for Pacific Islands Affairs, was simultaneously roaming the Pacific, peddling much the same message as Key - tend to your own lands, not Fiji, in a time of trial.
What Key got out of his trip was certainty that the other leaders would largely be singing from the same song sheet.
What the Pacific leaders got out of it was reassurance that Key would not neglect their interests - and the chance to make it just that little bit more difficult for him to make decisions based solely on bottom lines.
The difference in New Zealand's relations with the Pacific and the wider world was spelled out in an uncharacteristically sentimental paragraph in a Cabinet paper on the Pacific Agreement for Closer Economic Relations.
"In every other context, trade policy starts by putting the interest of New Zealand exporters first and aggressively so. In the Pacific, it is different. Here, our policy approach should start by putting our political, people-to-people relationships first. In some cases - Tonga, Samoa, the Cooks, for example - they are part of us."
A day in each country was not long. But it was long enough for the PM to learn the truth of that.
John Key emerged from his trip knowing he got on famously with the King of Tonga, albeit perhaps with a slight headache after being plied with champagne at 11am and then two hours of pre-dinner drinks later in the day for a dinner that went well past the scheduled 10pm end.
Samoa also won a little of his heart, especially the village of Poutasi, where he was met by the village men proudly wearing New Zealand-themed T-shirts as a tacit "thanks" for the seasonal labour scheme.
After just one hour in the village, they were offering him a chiefly title and he was waxing lyrical about the conch shell blowing at 6pm for prayers each day and 10pm bedtime.
Clark's greatest gift to Key is in the area of foreign affairs, where she drove home the importance of assiduously built connections and New Zealand's reputation as an honest broker.
He knows he cannot out-Clark her - but nor does he plan to squander what she has bequeathed him.