We were almost literally in the exact same scenario and era of home. We went with an 18", our first dishwasher in 8 years.
My girlfriend and I cook a LOT, so we make way too many dishes. On a bad day I fill up the dishwasher before my sink is empty and have to hand wash a few extra plates. I usually avoid putting pots and pans in there, honestly it doesn’t fit well with much else in the bottom row if you have that utensil thing in place.
If you only use a couple plates and a mug or two a day, its really easy to just put it in the dishwasher Instead of the sink and when full just hit CLEAN.
Was it worth it… I guess? How much do you hate dishes. Anything more than 2 people probably go bigger.