We've been up each of the last 2 years. Drove up in a TC in 14 and took the ferry back to Bellingham from Whittier. I doubt motion sickness would be much of an issue as a good bit of the water trip is on the Inside Passage in sheltered water. Even when in the Gulf the ships are stabilized and the ride is pretty nice.
This past year we took 22 days to drive up to Anchorage and 14 days to drive back in our motorhome(we pushed it coming home). Both years we spent at least 2 weeks there.
Anchorage is a good central base, but one should expect to visit for a few days in Denali, Fairbanks, Wrangle St Elias,all the Kenai peninsula, and Valdez.
The road trip is definitely doable by car or RV, expecting a few rough roads along the way.
Alaska is a "must visit" place so make sure you go somehow. Don't rule out flying and renting a motorhome up there.