Sunbrella is great for outdoor use - yes, it is expensive, but it doesn't rot in the sunshine like many fabrics would, and is strong and long-lasting.
Personally I would not use it for interior cushions. It would be an unnecessarily expensive choice for interior cushions (not a lot of UV down below), and I personally find it rough/coarse compared to other choices.
Thanks for the offer to let us know how many yards are required - it's one of those numbers which it would be great to have tucked away for future use.