Would you use one of those drains that you push to close and push to open. Sometimes I've seen them with fancy decorations on them, like a frog, or seashell.

Plumbing stores have click-clack drains to fit any size drain. Push it down to close, then push it again to open. We have one and I LOVE it.

-Babka

Just saw this video on a drain that might suit.

Here is a link that might be useful: Zero Drain video

I may just do the grid, but sometimes it is nice to be able to fill the sink. That zero drain looks interesting, too.

This may seem weird but I grew up in a house that had a deck mounted pop up mechanism for the Kitchen sink drains, so you never had to reach down into dirty water to undo the drain. This has made me a little squeamish about reaching down into "used" water to open the drain, and then I end up washing my hands again once the drain is open. Irrational, and a waste of water, I guess.

Another vote for the 'click-clack' type of drain. Bonus is it seems to seal the drain much better and more reliably than the pop-up kind.

I was squeamish about the click clack drain too. But stop and think for a minute. Why are you filling the sink in the first place? Aren't your hands already IN the water? Most likely it is soapy water...you push the drain to open and the run your hands under the faucet to rinse them.

All the pop-up ones I've had over the years wouldn't seal well enough to soak something for 5 minutes.

-Babka