[Laird Scooby]

Generally speaking, single earth electrode plugs are easier to adjust than multi-electrode plugs.

The three legs/terminals are the earth electrodes so from the point of view of being able to adjust the gap, i'd suggest you follow your idea and get single earth electrode plugs.

Unless it's a high performance engine with trick valve geometry and other things, there is little benefit in running plugs with multiple earth electrodes and the benefits won't outweight the extra cost. Same goes for Iridium plugs, usually many times the cost of the standard version and while they are capable of lasting longer, it's still usually cheaper to run standard plugs and change them more often.