I have posted this on the US board so I hope no-one minds me posting it here too....

We're looking at flying Continental from Shannon Ireland to Newark , 2hour 40mins layover then continuing with Continental to Seattle, arriving at 4.40pm (Shannon to Newark to Seattle would all be booked on one Continental ticket). We will have done US customs in Ireland prior to boarding our flight.
Then we are hoping we can connect with the AlaskaAir flight AS117 at 6.17pm to Fairbanks (booked through Alaskair).... do we have enough time????
I telephoned Alaskair to see what they have to say and the girl told me that we will not have to go out through security again.
She also said that Continental have a baggage share with them so if I ask on check in we should be able to get our bags checked right through (although I know from experience on other airlines it depends on the check-in person whether they will accomodate this or not).

Thanks,
Imelda

On paper, you have enough time. But that's assuming two earlier flights arrive more or less on-time. And the consequence is that you'll have to standby on the later flights to FAI; if you can't get there that day, you may have to buy a new ticket.

AS have up to 4 flights SEA-FAI in the summer, and 117 is just the 2nd of the day. I would book a later one and then standby on 117 if you get to SEA on-time. Give you a larger margin.

Gave pretty much the same answer on the US forum. I'd recommend not cross-posting.

You will find some useful information here:

http://www.portseattle.org/seatac/

I'm pretty sure than Continental and Alaska both use main terminal gates, so getting from one to the other should be a snap. If I am wrong, and one of the airlines uses either the north or south terminals, there is what we call the Underground Railway that runs every three minutes and connects all three terminals.

You'll be fine if your plane is on time. I live in Seattle. You won't have to deal with customs and if you get your luggage booked on through to Fairbanks it will be even easier. It is Customs and security that are taking a long time at SeaTac these days.The airport is fairly small and easy to navigate.