WeatherAlaska during late August is mild, around 5-20ºC depending where you go. Anchorage and the south were quite nice, at around 10-20ºC, but Denali was quite cold. All the areas were decently rainy. I think we got lucky and dodged most of it, having only rained hard one day when we were driving from Anchorage to Denali. It does drizzle often though, so make sure you protect your gear as necessary! The coldness does get to you while hiking, especially if it's raining, so bring gloves!
TransportationWe rented a car for the two weeks we are here. We got a Chevy Malibu 1LT from Alamo, which was quite decent, save for the abysmal quality interior plastics, which showed every scuff and scratch. Unlike the Prius rental from last summer, this car doesn't struggle at speeds near 80mph. The roads are incredibly well paved, have gorgeous scenery, are not crowded at all, making driving a pleasure.
CarI think this is common sense: to get the best photographs from the car, roll down the window to shoot! You never know how smudges on the window will ruin what may be an excellent photograph. Take care to use a fast shutter speed, otherwise you may get motion blur.
BoatA day cruise will mostly likely be in your itinerary; I went on two. They're fantastic for getting up close to glaciers and to see sea life. Depending on the size and then length of the cruise, you may have to compete for a good spot to shoot the animals. The decks are especially windy and cold in August, so dress warm so you can keep your good spot. The boat also rocks quite a bit, so image stabilization won't help much. You won't be close to the animals (at all), so bring a (super) tele! I was very sad that my 70-300L on an APS-H (1.3x) sensor was not sufficiently long.
ZooThere's a nice zoo in Anchorage that's worth checking out. There's no indoor exhibits, so leave the fast prime at home. However, do bring your standard and tele zooms, as you can get quite close to the polar bears and petting zoo animals.
Birds and other fast moving crittersYou'll want to practice AI-Servo or equivalent continuous focusing mode beforehand, otherwise you will get a lot of sort-of out-of-focus shots. Also good panning technique might be helpful if you can't shoot at a high shutter speed.
Mountain Goats/Dall Sheep
Sea lions enjoy lying down on rocks to absorb heat. They are easily heard by their bark.
Seals are timid animals. They highly enjoy sunbathing.
Puffins are pretty cute as well. There are two kinds in the area, the tufted puffin, which has crazy hair, and the horned puffin has an interesting horn-like pattern behind its eye. They dive under water to get the fish up to the surface, at which point they torpedo up and grab a fish.
These don't really count as I photographed them at the Alaska Wildlife Conservation Center. However, you might just get to see them sparring or bullying each other, which is a treat compared to lazily grazing.
These also don't count since I photographed them in captivity.
LensesFor this trip I brought along a 50 1.2L, a 24-105L on my 5D Mark II, and a 70-300L on my 1D Mark III. The 50 was mostly unused, save for some shots on the airplane. The 24-105 on the 5D is fantastic; you get an useful range for landscapes and other nearby things. The 1D3's crop factor on the 70-300 is quite nice, giving a ~400mm focal length on the long end, which turned out not to be long enough. To add insult to injury, the 70-300 does not support Canon's extenders. I wish I had gotten the 100-400; they're about the same price, but the 100-400L has a bit more reach and supports extenders, at the cost of being much older and weighing a bit more.
Carrying gearFor most of the time, I had the cameras around my neck, which worked fine. I wasn't afraid of rain since the 1D3 is fully weather sealed and the 5D2 is partially sealed. I stashed them into my Thule crossover backpack at the end of the day.
Misc.I had a Slik tripod that only got used once for a night shot of the starry sky at Miller's Landing, but the shot was accidentally deleted.
There were definitely deep pocketed amateurs or professionals in the wild.
Alaska Wildlife Conservation CenterThis is a little zoo-like area outside Anchorage along the Seward Highway. It's a pretty large portion of land in which animals such as musk ox and bears roam. It's somewhat expensive, but worth a visit.
There's not much in the city of Kenai, but there are a few hiking spots and a beach along Sterling Highway outside it.