For those who have done both trips, which would you choose if given the opportunity to only do one again? why?

I enjoy both and have done both more than once, but Alaska is wonderful. I just got back a couple days ago and it's just so peaceful there and the wildlife is amazing. I would head back up there again in a heartbeat.

Totally different experiences, each equally enjoyable. Alaska, for me, was more invigorating and exciting (did an independent coast and inland trip), while Hawaii is more relaxing and low key. Food much better in HI, accommodations dramatically better in HI. But our trip to AK was in many ways more memorable. Just depends on what you're in the mood for.

looking for a fun enjoyable trip with friends.
i love the mountains and feel i would enjoy the scenery more in alaska but wonder if hawaii is better with friends

Alaska hands down. I been many times to both but something about Alska that, like Travleis said, is invigorating and exciting.
And I love those long days in the summer

Big Daddy,
I lived in Alaska for 22 years and vacationed each winter for a month in Hawaii. Still go to Hawaii each year and visit Alaska friends at least once a year.
I love both Alaska and Hawaii, but I have to admit I am partial to Alaska. I think if you have never been to Alaska that you should go once. While Hawaii is lovely & nice, you can get a beachy experience in alot of shore places. Alaska is so big and beautiful and wild that I think you will enjoy the different experiences it can offer. Get out of the cities and see some of the wilderness and wildlife if you can. I believe that the uniqueness of the Alaska experience will be one you will talk about for years to come.

thanks for the comments!
I have done alaska only on a cruise and must admit I was a bit letdown.
the only reason is b/c my favorite place on earth is the canadian rockies and have done that many times.
when we did the alaska cruise we were on a ship most of the time and i didn't get to enjoy it as much up close.
i had this ideal dream that 70% of the cruise would be cruising surrounded by snowcapped mountains and glaciers - i would say only about 10% of the cruise is that way.
i do head to maui next week and am looking forward to it.
thanks for comments