Been to ESSA last year for a few days. As aviation enthusiast, I stayed at
Jumbo Stay, an old 747-200 done up as hotel. For me, booking through Expedia was a little cheaper then through their own website. At ESSA you have 2 shuttle busses between the terminals and the car park. Bus 'ALFA' stops in front of Jumbo Stay, bus 'BETA' is a little more frequent, but does not stop at Jumbo stay. The first stop on the car park, which is about a 5 minutes walk away.
Spots:
From the terminal, if you go to "Sky City" (shopping / restaurant area), you have some windows there with views on 01L/19R plus some parking spots.
From Jumbo stay you've got a reasonable view on the cargo ramp as well as a taxi bridge used for traffic to terminal 2 & 4.
On the
scramble map, I've been to spots 4, 5 and 6, all on foot. Keep a sharp eye out for the traffic when walking to spot 6 as cars drive very fast along the road. Alternatively you can take some forestry tracks by walking along the landing lights and going north of the lake. As a bonus you get a limited view of some of the general aviation & maintenance aircraft parked there.
Bus BETA will take you to 'Driftvägen', which is least walking. Or you can take bus ALPHA to Tullvägen (I think), "Police & Customs" on the English announcement.
Another tip: Patria Helicopters (near spot 6) have cafe area where you can get decent meals for a decent price (keep an eye on the opening times though, only during lunch time).
I didn't visit ESSB, so no advise for you there.
Hope this helps with ESSA.