I just came back from a week of cruise and 2nd week on land. During our self-guided 2nd week land tour, we drove roughly 1,300 miles and spend nights at 4 different hotels.
The long daylight hours actually never affected anyone in our party of four. For us it was part of the unique Alaskan experience. Just make sure you plan to do enough outdoor activities to tire yourselves out then sleeping won't be a problem.