BOS terminal E to A
 

Is two hours a realistic connection time from an Icelandair KEF-BOS flight that arrives at terminal E to a Delta Connection flight that departs out of terminal A?

I do have global entry, but I will be checking one bag (no way around it, due to containers with liquids).

BOS customs has always been lightening fast for me. 2 hours with GE is plenty of time. 5 mins or less on the transfer bus.

Is the transfer bus worth it? I walked A to E the other day in maybe 10 minutes, didn't have to wait for a bus, etc.

In my opinion walking is easier unless you are overloaded with bags. All the terminals connect thru Central Parking on Level 4. So just follow the signs to Central Parking and then follow the signs to A.

At busy times the buses can be quite full and a hassle but they will work too.

2 hours is definitely enough time with Global Entry. Otherwise, it will still be doable but if it is a busy time you might have to hustle a bit.

OK, so as long as the bag I have to check doesn't take forever to arrive, two hours connecting time should work out well.

Don't forget the DL bag drop deadlines, especially if you cannot check the bg through and drop it just after customs. I suspect (but did not check) that Icelandair doesn't interline with DL.

For these questions, it always helps to know whether the person has one ticket/PNR or two separate ones.

Another vote for walking. A-E via central parking is one of the easiest connections between terminals at Logan.

Once you exit customs, take the escalator up two levels following the signs to Central Parking. That sky bridge and hallway, if you keep going past the garage, then leads over to the A terminal. Before they started building that second garage, it was a great place to look at the planes in terminal E.

FI and DL interline (in fact, I used that on the way here).

This is two tickets and two PNRs, I could not get DL to issue a ticket on FI, they insisted on crossing the Atlantic on DL/KL/AF and then connecting somewhere in Europe to an FI flight. The MQMs would've been nice, but the fare got really stupid really fast.