Although I'm upgrading to a really big sink in my new kitchen (custom soapstone), I've had a 21 inch single sink for the last 17 years. Cooking daily for my family of 5, I have to say it's done everything I needed a sink to do. I wouldn't want it to be any smaller though. I handwash very little and always have a dishrack on the counter to hold drying items or draining pasta or just-washed fruit.

If I wasn't adding on to my kitchen, I'd be keeping that size sink for sure. My opinion is that you'll be fine!

I hope that helps.

My DD is just finishing up her kitchen remodel and went for a 24'' sink base to allow for extra cabinet space in the corner. She's putting in a d-shaped sink, only 18'' wide. She never leaves dishes in the sink (a real neat freak) so I'm sure she'll do fine. When you think about it, I have a double sink, both sides 14'' wide and I have no problems washing anything big. But I'm NOT a neat freak and the other side just holds stuff left for drying! I think a single bowl forces neatness!!
I'm sure you'll have no problems!

Our old kitchen had a 21" single bowl and was fine -- used it for 12 years and thought seriously about sticking with a similar size for the new kitchen, but really wanted to add a small 2nd bowl (just for drying). In the old set-up I always had a drying rack on the counter (we had a wall behind the sink), but the new kitchen is open (no more wall), so the sink is on a one-level island and I just didn't want a dish rack on the counter anymore.

Have had 21" single sink for past 12 years, no dishwasher. Have survived just fine but it's just the 2 of us (no children). Now we're about to step down to 18" single sink (Julien 18x18 square) cause we're laying out the new kitchen differently and we're getting a dishwasher. Sink/DW wall is only 8 feet and we want the extra inches in the corner susan and in the cutting board cab. Hope we don't regret it. I doubt we will, now that we'll have the DW to stick the dirty dishes directly into.