What I'd choose is a configuration that supports easy washing. To me that means removable and better yet double sets. Remove a piece to soak in a laundry tub. Replace it with the spare. Sunbrella has a broad range of choices to fit your overall color design. If you don't sew, marine cushion fabricators do this work all the time. Latex is much more long lasting for cushion material.

show a sketch of what you propose for the bench / the back of the bench/ the overall dimensions and what the corner is like generally. there are many ways.....some can be very inexpensive... some ideas are quite custom....some quite durable........some less durable but could be replaced when kids grow up a bit and cheap enough so replacement isnt a big deal..... I've sourced foam quite easily and made various cushions and covers with all kinds of fabrics .... you can cut the foam to size .....

of this assortment..only the last two would be out of reach to DIY . the various others can be DIY and not hugely expensive so if replacments are needed not a biggie. Using patterned fabrics hides difficult stains that dont come out entirely..... but you can treat fabric

Thank you both for advice! Marine/boat cushions are kind of the look/feel that I’m going for if we go the upholstery route… not as beautiful but durable and very wipeable. I’m sure this material is pricey though.

Here is a drawing of our bench and a general concept/inspiration although I am not planning any back cushions, just possibly a seat cushion.

The seat height has to factor in if you are using a cushion or not. And what type. Otherwise, you will either have a too large gap, or your legs will be squished against the table.

Wow, I do worry that upholstery of any kind will be hard to keep up with for a few years. Spot cleaning isn’t going to really do it.

Currently I have found some retailers that make zipper covered outdoor foam cushions. From cheaper cost/ quality to higher end. But if they’re tailored fit, it’s hard to wrestle the cushions Bach in, especially bigger/ longer ones.

I wonder if a looser, less tailored fit cover in highly washable fabric might work— for a custom banquette, probably needed custom. Vs a semi- custom fit from a company something like Surefit slipcovers, or with elasticized corners. Or a folded flat sheet ( or crib sheet?) plus those stretchy- clip thingies that go on underneath , you can get for air mattresses, to hold it in place.

This would be for over top of your best idea/ value for the actual upholstery, or perhaps buying a lower- end cushion that you expect to toss after a year or so. You can see I’m really focused on actual washing! Based on my children years ago, and now grandkids.

I’d also think carefully about the color. Many clear solid colors will show spots like crazy. But perhaps the newer specialized fabrics are truly very stain- resistant.

Sunbrella lengths are periodically listed on ebay at more reasonable prices.

Have you talked to an upholsterer? They may have recommendations for a leather-like fabric.

A good quality vinyl will last years of wiping down. Choose a medium or dark color that won't show spaghetti stains. An upholsterer can order samples for you to test with spaghetti, orange juice, etc. Burgundy, forest green, and chocolate brown are practical colors.

An upholsterer can make a cushion with a sightly slippery fabric covering the foam, so that a the slipcover slides over it readily. The outer slipcover fabric must be preshrunk (unless it is vinyl or some other unshrinkable synthetic) before being sewn up. Specify a nice long full length zipper that also wraps a few inches along the short sides so that it is not a struggle. Plan to replace the cover in five or ten years or so.

Yup, first thing I thought of. Naugahyde.

Agree that a local upholsterer can probably do this, or you can find people on Etsy who will do some basic shapes at reasonable prices, especially if you can build it from rectangles...