good/bad experiences booking with Skyscanner? Customs questions

Immigration, passport control, takes much more time than Customs. Get Global Entry to get through quickly. Customs is where you declare the purchases you made abroad for possible taxation, usually $800 worth is tax free.

Skyscanner is an aggregator. Search results will display the airlines and scheduled flights along with the supposed lowest price based on your search. It'll then display the booking agents including both the airlines and potentially sketchy third party vendors. Keep in mind that Skyscanner is not a booking agent and is not selling anything and that third party vendors are paying to show up in results and are not vetted by Skyscanner.

Personally I'd only ever use Skyscanner to get a general idea of airlines serving a route and general pricing, then I'd go to the airline's website and buy direct.

Personally I'd only ever use Skyscanner to get a general idea of airlines serving a route and general pricing, then I'd go to the airline's website and buy direct.

THIS.

Same here. Much safer/more reliable.

Choose a longer layover than 2 hours if you know you would be ruined by the choice of the less expensive shorter connection

Actually, if you choose the option of an airline’s own price on Skyscanner, they send you to the airline’s website for the purchase. I have done this several times. My cc charges were from the airline; all transactions, e.g., seat choice, upgrading to economy +, done with the airline’s site. There was no 3rd party involved. When you get to the airline’s site, all the flights are displayed. You can match up departing and returning flights any way you choose.
Some of the responses on this thread are provoking me to protest against posters who confidently make assertions about matters with which they have had no experience. It is a not uncommon occurrence, and singularly unhelpful.

Is your Rome-HNL trip a single booking?

If so, the airline should be aware of what amount of time the immigration takes and has planned accordingly. To be sure, contact the airline and ask them what happens if you miss the onward flight because of a lengthy processing time at immigration. ( i.e., do they put you on the next available flight at no additional cost, or are you obliged to buy a new ticket)

If you are cobbling together two bookings then 2 hrs is way too little time.

Global Entry isn’t necessary (although it can be enormously useful if you travel abroad a lot). If you don't travel out of the United States enough to pay the fee and make the appointment, you can use the Mobile Passport app offered by the CBP for free. It's worth checking into, at least.

SkyScanner is very useful for Europe's budget airlines which may not show up on other international on-line agencies' searches. It is dead easy to pick the link to the actual seller, which usually includes the airlines themselves. They also show some budget airlines in Asia. My searches for trans-Atlantic flights have found less comprehensive results.

2) Customs timing: Looking at return flights from Rome to Honolulu,
via LAX or SF and wondering: We go through customs in LAX, I assume?
How much time should we leave for this? Options have 2 hours and 10
minutes between long transatlantic flight and the LAX to HNL flight --
too short?

Too short? Customs is a mere walk through unless you have purchases to declare and thus taxes to pay. You don't need to allow 2 hours and 10 minutes if you aren't declaring any items purchased. You don't need to allot any time! Just walk!!

As for airline ticket purchases, do what others have said and feel free to use 3rd party websites like Skyscanner for pricing and then purchase tickets with the airline directly.

Have a great trip.

If you fly Rome to LAX to HNL, you will go through both immigration and customs in LAX. The immigration line can be long or short, and how long it takes cannot be predicted. It depends on how many agents are on duty, and how many other international flights arrived at your terminal at the same time (and at LAX, there are always going to be other international arrivals). You then pick up all your checked bags, then go through customs. In the US, there is only one customs line; you can certainly be stopped for additional screening (although it's only happened to me once, returning from Hong Kong via San Francisco). Just outside the customs door, there is a baggage recheck desk, where you deposit your checked bags so they'll be put on your next flight. You then make your way to your next flight, going through security on the way (since you've left the "sterile area").

All of this takes time, particularly if you have to change terminals at LAX. I agree that the Mobile Passport app can save oodles of time (at least it has at JFK and Newark the three times I've used it), but I would still allow several hours for all of the "formalities." One advantage you have is that there are multiple flights per day on all the airlines between LAX and HNL, so if you do miss your connection due to a late arrival at LAX, you should be able to get a flight home later that day, rather than having to wait until the next day. As long as you're all on one ticket, and as long as the missed flight wasn't your fault (i.e., you didn't miss the flight because you were busy shopping), they should put you on the next available connection at no extra charge.