When you drive back from Seward (Kenai fjords), I would suggest a side trip down the other side of the Kenai Peninsula to Homer. You pass through Soldotna and over the Kenai River on that trip. Fishing is winding down by then, but the drive is beautiful.
Homer is an "artist" community with several galleries & museums. There's also the Homer "spit", the longest one in the world. Neat place anytime & the weather should still be good then.
Going north is an option also. The Glenn Highway has been named a scenic highway by the feds, fro very good reasons. You pass Matanuska Glacier & see some very pretty country on that drive.
Have a great & fun trip!!!