As a former Alaska resident I second pretty much everything I've read above. I'll add a few comments.
August (four weeks) driving from Texas will be a very rushed trip. I've driven the highway several times in the last few years and 500 miles a day is about all I wanted to do. Alaska Hwy and the Cassiar in BC, Yukon and Alaska are two lanes. Some sections are better than others but don't expect 70-80mph all the way. July and August would be much more relaxed and you'd have time to do more exploring.
In Alaska you can camp pretty much anywhere you can pull off the road. Canada is more restrictive and I've never seen roadside camping like in Alaska. Canada Providential Parks are nice. Get some Loonies for the showers.
The Milepost is your best road resource. It includes a lot of information about the roads of course but also has sightseeing, camping, lodging info, etc. too. When you see a Rough Road sign in Alaska SLOW DOWN. They mean it. The Tok cutoff from Mentasta Lake to Chistochina has frost heaves that double as alternate NASA launch sites (unless it's been repaved in the last year). Be cautious of the hill just west of Slana. The Richardson Hwy north of Glennallen (to Black Rapids) has some bad road too. The Glenn Hwy east of Sheep Mtn Lodge has some good frost heaves and it's very narrow with lots of blind hills and curves from where the road narrows west of Hicks Creek to Palmer.
Check your cell phone carrier for Canada coverage and cost. Last time I drove through, AT&T didn't have coverage in Canada. T-Mobile did but only around towns. AT&T works in Alaska on most of the main road system.
Mid August is a little late for most salmon on the Kenai though there should still be some Silvers and Pinks but every year is different. Salt water fishing should still be good (halibut, yellow eyes, rock bass and ling cod). Any clear water stream and most lakes should have grayling and/or trout. Alaska is very serious about fishing licensing so don't wet a line without one.
I'd recommend a stop at Liard Hot Springs (In BC on Alaska Hwy.). Nice campground but can be crowded and the hot springs are small but fun.
I second visiting the McCarthy/Kennecott area. Explore the mine and hike out to the glacier. Might as well visit Valdez too. Spectacular scenery and good halibut charters from there.
The Denali Hwy (Paxson to/from Cantwell, not the park road) has great scenery and wildlife viewing plus some great camping spots.
Seward and Homer are great places to visit. Kenai Fjord tour from Seward and fishing from Homer.
I seem to remember an article in the Alaska Daily News that the last unpaved section to the Haul Road was getting paved this year? If you drive it, manage your fuel. Coldfoot is the only fuel stop much past Livengood (check the Milepost). You can't actually drive to the Arctic Ocean. You have to do a tour (if available). Oil areas have restricted access.
Broken/cracked windshields are a luck of the draw. Less common in the summers on paved roads but can happen any time a vehicle passes either direction on gravel or chip sealed roads. Watch out for dump trucks!
Ferry system is an unknown. Budget cuts are wreaking havoc and quite a few of the ferries are older and having maintenance issues. Have contingency plans in case your reservations are cancelled. I'd only take the ferry one way, lots of fantastic stuff to see on the Inside Passage and on the Alaska Hwy. If you do take the ferry, vehicles and people are separate costs so make sure you have a reservation for your vehicle AND you. Vehicle costs are based on vehicle length including anything attached that extends past the bumpers (equipment/cargo racks, canoes on top, etc.).
Good luck. It's a great drive.
Those of you that have traveled to Alaska and driven... did your dog travel with you? If so... any pros or cons? Secondly "If" you do take pets and use the Ferry how does pet deal with the long ride and potty break?
