I find that for me, one day is sufficient but it depends on wether you want to see all the demonstrations or just the odd one or two. They are usually very good shows, but best to get there 'before time' to sort out your timber and there are usually plenty of trollys available to load up. Make sure you park near the entrance, as you come out that way with your goods, just tell the attendant that you need to be close for the timber load, otherwise it's a pain wheeling the trolly over all the rough ground. The selection of timbers is really great and often a lot of the 'good bits' go early, with loads of big open boxes of offcuts as well.
The next show is the 8th and 9th April, so get it in your calendar and have a load of fun with your plastic card.
Malcolm