It would be helpful to know what part of the world you live in, just to know the climatic conditions, but lacking that info I will tell you that we're coming up on a good time to buy furniture that might work in your sunroom. I'm thinking about the faux wicker furniture that will be going on sale in July. Real wicker would be better if you can find it. The reason I like wicker is that when it comes time to recover it, it's only a few cushions instead of a whole sofa or chair.

Restoration Hardware usually has some good looking faux wicker tho it tends to be very large in scale so their "dining chairs" are about the size of other people's lounge chairs, making them a possibility for your sunroom.
Craig's List is another possibly good source for you.

What I actually drew for you below is about as simple as a furniture layout can get: one sofa opposite 2 chairs, with a small table between the two chairs and a very small coffee table in front of the sofa. Not knowing exactly where the doors and windows were located, I didn't draw them in. Instead of the sofa and 2 chair arrangement, you could use 4 chairs and a round coffee table in the middle of the room with the chairs around the table.
Carolyn Albert-Kincl, ASID

Thanks so much. I live on the east coast, outside of Boston. If it would be okay with you, I could take a picture to give you a clearer vision. Once again, thanks.

A photo would be ever so helpful, and two would be even better.