Well, it looks like most people gave alcohol (or chocolates). As a non-drinker myself, I wouldn't know where to start when it came to giving a bottle of wine. But thanks to everyone who has replied so far. Keep those suggestions coming!

As for whether or not to even give a gift - I agree with sezjm: since the service was excellent and I was really happy with my care I'd like to give a gift because I can. I'm a health professional too, and when patients have given me thank you cards (one even knitted booties for my baby) I really was chuffed. Sometimes you put in a heck of a lot of hard work and rarely get any feedback that you are doing a good job. The odd thank you card can make it all seem worthwhile.