It's hard to know where to start attempting to list what's so good about this place: just about everything is.
First, the look of it and the layout: it's all very zen, with clean minimalist lines softened by the use of warm teak detailing. On entry you are taken to the stylish Club room for snacks as you sign in and your luggage makes its way to the rooms. Downstairs there is a soft-furnished and candle-lit seating area overlooking a lily-filled pool where local music adds to the evening atmosphere. Further on are separate areas for the restaurant and the pool, which are both near the swift-flowing river.
On to the rooms: we had 2 suites, which were very spacious with a king bed and a large day-bed so the kids had a large bed each. They also greatly enjoyed the inclusive minibar, doing their best to set a consumption record. The view was over the pool and the river, and was very attractive. The only thing that was slightly awkward was the arrangement of the bathroom doors: designed so that the bath could be either open to the room, for the romantically inclined, or closed off for those who prefer privacy, it was a little difficult to manipulate and made the space a little echoey. Nevertheless, just the sheer amount of space and in each suite was exceptional and we all felt very comfortable all the time, and visually it was all very pleasant.
The restaurant definitely deserves mention. You would expect that they would serve fine Thai food, which they do, and there is a range of light and spicy salads as well as the more usual meats and curries. As a bonus, however, they also do marvellous Indian food, including delicious dahl and excellent warm fresh breads along with good renderings of favourites like butter chicken. What sticks most in my mind, oddly enough, is the bread that comes at the beginning: you would expect a hotel in Thailand to provide quite the most tasty European-style bread you've ever had, but they do. Bear in mind, I'm not a carb freak: I don't think I've written much about bread served in other places, but this was so exceptional even amongst all the other wonders of this place that I have to mention it. The ambience of the place was romantic in the evening too: try to get a table overlooking the river, and if you go later (after 8) it's unlikely to be overly busy. The same restaurant does a decent breakfast in the morning, although with every guest attending it's rather more crowded and less atmospheric, but still better than most (e.g. individually ordered rather than buffet eggs, which always helps).
Fortunately with all this culinary excellence, the Chedi also has one of the best hotel gyms I've ever had the pleasure to use: lots of cutting-edge cardio equipment, a good selection of weight machines and free weights, as well as a yoga room. Like so many of these high-end places, hardly anyone seems to use it, which is even better.
We took a number of tours arranged by the hotel, around the City, to Doi Suthep, to an elephant ride and on a very long day all the way around the Golden Triangle. Whilst I suspect we paid at least double the rate that could be negotiated outside the hotel, it was all very well done with a patient and knowledgeable guide whom we gave a nice tip at the end. Pickup and return to the airport were seamless and faultless too.
All in all, this was an excellent and memorable experience and (other than the tours) really not bad value at all, given the quality. I would recommend a sojourn at the Chedi to anyone who can afford it.