changing spark plugs seems to be the only major PITA maintenance item. all else are relatively easy. the size of the engine relative to the engine bay also makes it easy to work on than most cars. so the way i look at it is that changing the spark plugs vs. all other replacement items sort of balance themselves out. but with all the advantages the FRS/BRZ has to offer, i wouldn't let the difficulty in spark plug replacement be an influential factor when buying a car since it doesn't get replaced often enough.
if you ARE going to replace your plugs, you might as well go with good ones. i recommend using denso iridium IK22's. not sure if you've got them over-the-counter but i had to get mine from a tuning shop. it's what the tuner recommended. also they are just rebadged TRD plugs
