Coleman Xtreme is the answer.

Yes, get a Coleman Xtreme 5-day cooler and stop overthinking it.

It’s $50–$70 depending on size, keeps ice for a day and a half (easily 8 hours), and has thick insulation. The lid seals tight, the drain plug works, and it’s not overbuilt like a rotomolded cooler you’d drag through the wilderness. For a picnic, this is all you need.

You don’t need a Yeti or a Pelican. Those are for week-long camping trips or serious abuse. For a sunny Saturday in the park with sandwiches and soda, a good $50 cooler does the same job. Spend the extra money on better food.

Your potato salad will survive.