Are you talking about covers to protect the furniture over winter or something softer like you'd have on indoor furniture? I use Veranda covers (by Classic Accessories) all year round because it keeps the chairs and cushions dirt/dust free so when we do want to sit outside we don't have to go through the ordeal of wiping things down first. Just throw the cover off and you're good to go. Here's a link to the chair cover, they have many options to chose from depending on the size/style of the furniture.

Another idea is to buy oversized terry cloth beach towels and drape them across each piece of furniture. When they collect too much dirt they go into the wash not the cushions. I do that with the chaise lounge. Sometimes the wind kicks up and blows the towel off the lounge. So now I attache metal chip/bread bag clips to each end and they help weigh the towel down and keep it in place.

I'd like to have slipcovers for my patio furniture too but I think the only way I'll get them is to sew them myself, haven't seen anything like that in stores. In the meantime I'll leave the heavier covers on. Anything to keep from having to constantly clean the furniture!

Here is a link that might be useful: Veranda covers

well speak of the devil, look what I saw today in the Solutions catalog that arrive in the mail. They sell covers for plastic patio furniture. Never seen it before and now that you've asked about it I see it! It's so hard to buy covers to fit perfectly because furniture is made in all different shapes and sizes so this may not work for your furniture but it's a nice way to cover up cheap plastic chairs.
BTW...Are you there or am I talking to myself?

Here is a link that might be useful: Klassy Kovers

Years ago many of the catalogs featured slipcovers for the plastic patio chairs that came in solid and striped fabric. They were inexpensive, even came with a seat cushion, and were durable and easy to wash. When I wanted additional sets, the stores I purchased from had discontinued this item. When I researched purchasing another type of cover, I came across the Klassy Kovers mentioned and linked in another post. They're great, look good, wash easily and make those old plastic chairs look terrific.

I just got back to checking this board. Thank you so much Flyingflower! This is exactly what I was looking for! You can always count on someone on this board helping you out! Thanks again!

I'm not sure which one cricket liked?! Klassy Kovers or the Veranda covers?

I'm glad you posted this too, I JUST today scored a great set of resin wicker furniture (black) with red cushions. This set was in a covered patio, my patio area is only partially covered with a pergola, but those red GEORGIA colors will surely fade in our hot sun...I am considering doing another lighter patterned fabric for them...which has UV protection built in or something like that. anyhoo...I'm a lazy sewer, so I'd love to also do more of a slip cover, something that would be quick and easy to get off for washing.

anyone able to offer some design/construction suggestions??