We have done both a land only trip (driving from Alaska to Kenai Peninsula at the South and also up to the inland to Denali National Park at the North), as well as a cruise.
Whether you get to enjoy Alaska LARGELY DEPENDS ON THE WEATHER. Unfortunately the weather in Alaska is TOTALLY UNPREDICTABLE.
The season starts in Mid May for cruise and ends in Mid Sept. In theory the best time of the season unsurprisingly is between mid July and mid August.
We did our land trip in early August, yet the weather was so rainy all the way we did not get to see Mt. Denali at all - but we saw tons of wildlife in Denali NP. Also we did a day cruise (costly, $120 per person) out to Kenali NP and got to see Tidal Glaciers upclose. Saw lots of calvings and whales and orcas.
We did our cruise last year in early Sept. It rained from day one to day six and while we took Princess cruise for the sole purpose it is the ONLY cruiseline has license to visit Glacier NP, we did not see any calving, and only a few seals. But cruise was very comfortable and very economical.
The 5 day land trip we took few years back, rental car and lodging and gasoline and foods, costed us MORE than the 7 day cruise trip we took last year before the shore excursions. Shore excursions can be very expensive if you opt for those - then again, if you do the same things on a land trip they are about the same. Such as a float plane ride to land on the Glacier, can cost you $200 to $300 a person.
Rental car is expensive in Alaska. One day rental we did at Sakawag as we wanted to drive to Whitehorse, Canada - with a very special code we got an Avis car for $45 but without the code, the car was $75, rental only before any tax or insurance.
Lodging runs about $120 to $150 a night if you use Bed and Breakfast.
But, HONEST TO YOU, WE THINK ALASKA IS WAY OVER-RATED.
It carries the mysterious air because it is so far away - but in reality, the Northwest and BC of Canada has much more beautiful natural scenaries than Alaska. Though if you enjoy fishing, then Kenai Peninsula is a very good place to go and very beautiful too.