I spent two weeks in Kalpitiiya three months ago and had a blast. I had the most basic accommodation at
www.srilankakite.com run by a pro kiter and tester for North kites called Fabio. Watching him kite is a real treat. The room without bathroom was from memory 35euros per night but including all meals, which are buffet and mostly Sri Lankan food with the odd night having pizza. They've just upgraded the communal shower area too. It was perfect for me or a couple on a budget and I met loads of great people.
From what other kiters told me about their centres, it was by far the best kite centre in the area. But I didn't see the other centres in person, so can't say this with 100% confidence. But the one I stayed in comprised of rustic local construction huts and rooms with more primo and family sized huts if you want them dotted about the sandy complex. A nice open air communal dining area. And best of all a cute little open air bar which we got going at night, run by Fabio and his partners. All very relaxed up for a laugh European guys. There were a lot of Europeans there who like a party at night, so we cranked up the stereo and drank and danced until am most nights. It was the only place in the area that had a party at night. No restaurants in the area either.
The lagoon is sweet. They take you over by boat to the other side and bring you back for lunch and diner. You can kite directly off the kite centre but it can be tricky as the wind often comes off the land behind the centre and trees (depending on what time of year) and can be lumpy. But they have the best spot on the lagoon, with other centres further away and needing to truck people in for their sessions.
There's also a totally fabulous day trip by boat for another 60euros to the "dream spot". About an hour by boat, (they're also planning to turn it into an over night camping trip). But basically a sandy crescent shaped bay on a remote island northwards in Puttalam lagoon. A huge 1.5km run with wind coming over the island uninterrupted by any trees or buildings, so really smooth and consistent. The water on the leeward side is totally smooth and shallow and I would say it is by far the most perfect spot I've ever kited. (Not that I've been to Brasil). But regardless it's awesome. You can practice all your tricks here so confidently and two boats to keep an eye on you and retrieve you if you get into trouble.
But there really is nothing else to do in the area. It's surrounded by salt flats and rubbish strewn palm forests. There is a small town nearby but you can look around it in half and hour, so it's more for getting supplies like the chemist. You might want to spend only a few days in this area and then head to Aragum Bay where there is more for non-kiters, and waves if you want to break things up. Your girlfriend would really need to have lessons to occupy her time as there isn't even a decent beach to swim on at the kite centres in Kalpitiiya.
More details here on Fabio's facebook page:
www.facebook.com/ingrossof?fref=ts