Find light patterned fabrics that are mostly light toned (warm whites or ivory based) but have brown as the or one of the lesser accent colors. Use a 3rd color (maybe a green or a blue to get the coastal vibe or maybe red to go more tropical) as your main accent color. So, for example, use an ivory-toned toss pillow along with a blue/ivory/brown pillow and a light-weight ivory throw with blue pattern or fringe. Blue sea glass and driftwood pieces could be your decor if you go ultra coastal. Or go with any blue accent pieces and wood boxes or bronze metallics for a less coastal look. Wood flooring or a beautiful rug that includes touches of brown is a more expensive route, but very effective in creating balance with this type of color challenge. Then you can take the light tones along with that main accent color with or without the brown touches to the rest of your rooms in the art and decor. Some use of brown in the rest of the room with the couch will give the room balance without making it look like you're trying to hide the biggest piece in the room as it might if you just ignore the brown color and cover that son of a gun with light colored throws and pillows. Here's a shot of a similar challenge with a beloved gray leather love seat in a coastal living room using grays, blues, greens and silver. Good luck, send photos!

Sherwin Williams Sea Salt is a good FL color and a great neutral paint color

Would love to see photos of the room, but I live in Fl also and see lots of rooms with dark brown sofas. Depends if you want a coastal look or just a light and airy décor. Lots of people use the ratten furniture in their living rooms and it would blend nicely with the sofa. I would keep the walls a creamy beige and accent with the colors of turquoise, yellows or even orange to lighten up the area.