There is NO advantage to seeing Mendenhall Glacier, only that it is more well known. ANY glacier landing is spectacular on the Juneau icefield, in a constant state of change. These are run by different operators- ship contracted. I would also suggest you may want to consider booking independent with Coastal out of Juneau, an excellent company of which I have flown with 3 out of my 6 glacier helicopter landings. The one landing is $180. It allows you off the helicopter and you can walk as little as you choose- no ice climbing or trekking.