I last rode the GT in Sept. '09 and it was great. The new bridge east of Golden is in good shape although there was still some construction east of the gorge. Overall the road conditions were fine.
The weather in May is pretty unpredictable. I guess the Elbow Valley club ride has had pretty bad conditions the last couple of years.
The hostel at Castle Mountain is a good place to stay, just east of Lake Louise. If you prefer to camp there are a couple of nice little spots along the 1A.