I have to say that is an incredibly thoughtful gesture. I would go with a little something for the baby and a GC to a restaurant with take out or delivery service. I would also, if you have time, buy a pretty journal and write down any pertinant information in regards to the house (ie: plumbers, electricians, paint colors and brands used in the house (that was very helpful when we moved into our house) and maybe some local information (ie: good restaurants, stores, points of interest). Then after you have put your information they can use the rest of the book to put their history in. We keep our journal and every time we have some work done on the house we log the date, the vendor who does the work, what work was completed, the price and the compay's phone number and address, it is a great reference tool for us.