score:4
It makes no difference if the first flight is United or Swiss as long as it's a single ticket from ZRH to Kona.
In either case, you need to collect your bags, clear US immigration and customs and recheck your bags.
1.5 hours is tight but doable unless your incoming is delayed or lines are unusually long. Personally I would go with the 2 hour option.
If you miss the connection, United will put you on the next flight to Kona. It may be worth checking if there is another one later the same day. If not, you'd have to stay overnight in San Francsisco
Upvote:0
I would not worry.
Often intercontinental flight arrive earlier. Timetable are about bad (but not extreme) conditions. Delay are departure are usually shorted for intercontinental flights (usually they do only one or two flight per day)
But things could go wrong. It happened to me. Bad weather and immigration was so long (1 hour waiting) so I arrived at gate late (airplane already departed).
I asked some people of airlines, and they redirected me to the right gate, where I got the boarding pass for next flight (so just one hour delay). I think it is was the best solution. By hurrying, you risk to wait at arrival airport for your luggage, which have more probability to miss flights.
So be prepared to miss the flight, and maybe bring some essential items (for one night) on you cabin baggage, but do not worry too much.