Depends on what type of fishing you plan do to but if your in Valdez, you can pull off the road around Allison Point and fish for pink salmon. Not sure exactly when that run is over but you may be able to hit the tail end and get into some fish. Pick up a copy of the Highway Angler off Amazon for a run down of all the fishing to be had from the road system. Definitely worth the $30.
Unless you are a big fan of driving, that is a fair amount of windshield time. If you run down to Seward and stop in Girdwood either down or back, The Double Musky is a good place to eat though pricey. From Seward to Valdez is a solid 8 hour drive if you don't stop but you will want to, often. The Glen hwy is very scenic so lots of good photo ops if the weather cooperates.
Valdez is a nice little town and if charter fishing is on your to do list, there should be plenty opportunities. From Valdez, if you go up Hwy 4 to Fairbanks, that's another good 8 hours. Not sure of your rental agreement, but if it doesn't specify anything about off pavement driving, the Denali highway runs ~130 miles from Paxson to Cantwell. Excellent fishing to be had along there. Maclaren River Lodge is a decent place for refreshments and good place to stay overnight if you're so inclined. Pretty decent fishing around if you don't mind walking a bit. If not, Delta Clearwater a few minutes from Delta Junction is a good fishing spot. Its better with a boat or canoe but I did good in waders.
Fairbanks area is one of my favorite places. The Santa Clause house in North Pole is a popular spot and if you get out towards Fox, the Howling Dog Saloon is a colorful spot for a cocktail. The Silver Gulch, across the street is a brewery with some decent beers. Food and service can be hit or miss, at least that's been our experience the last few years. We usually end up at Ivory Jacks down the road, better food and service, IMO.
If you drop down Parks Hwy towards Denali, a stop at 49th State brewery in Healy is worth the time. Its only about a half hour before Mckinley Park. If your time allows, a stop in Talkeena is another fun little town.
Of course there are streams all along and that's where the Highway angler comes in handy. Keep in mind that it can start to get chilly late august/early september, especially in the interior.
