I'm pleased GB didn't draw Spain - that would've been so tough! Croatia seems a winnable tie provided Andy plays. There's very little turnaround time from the US Open though - if Andy plays the final again (and hopefully he will!), it'll be on a Monday and then the Davis Cup starts on the Friday. I wouldn't be surprised if Croatia choose clay as well, so there'll be the added difficulty of adapting to a new surface.
Croatian journalist Gordan Gabrovec tells me they have only ever played one home tie outdoors, 17 years ago vs. Australia. Lost 1-4.
Usually favour Hard courts I believe.