Very impressive joinery. I like how you attacked the beams to the cedar posts. I still worry about attacing anything to the end grain, but think your method and the size of those spikes should work very well. I'm in the early stages of building a gazebo with cedar posts and love to see how others are using them to get ideas and hopefully make mine even nicer.
Did you sink your posts in the ground? Here, in my red, clay soil, cedards start to rot in the ground in a few years. I have two cedars that I did that for my front porch that are rotting on me and I will have to pull and do differently sometime soon. For my gazebo, I'm going to pour a cement footing with C channel in it and sticking up two feet. Then drill two holes in the C channel and put 3/4 inch carriage bolts though the cedar logs. My thinking is this will lock them into place, keep them off of the dirt and allow the end grain to dry out after a rain. I can also replace them easier this way if I have to.
Keep up the pics. It's looking like an amazing project and one that I want to follow to the end to see how it turns out.
Thanks,
Eddie