You won't need reservations at that time of year except if you want to reserve for Denali's Teklanika campground (highly recommended). Purchase the TEK bus pass and ride the bus as often as you want from the campground. Go out an hour or two in the morning and again late afternoon or go out all day. We've also gotten off the bus and just walked along the road until tired then caught the next bus coming by. They run regularly. You would not believe the absolute silence and awe you'd have!
I'd prefer your Valdez route rather than Fairbanks. If you have time do the Stan Stephens glacier tour out of Valdez. It's great. All the loop roads would be snow-free that time of year. It's a beautiful time to be there. If, by chance, it would snow it would be light and would melt fast but I highly doubt it.
Out of Anchorage on the way down the Kenai is an awesome national forest campground called Williwaw. You can walk to Bear Glacier - takes about 15 minutes and easy.
Have a great trip!