I often travel solo, and I highly recommend the Glion SNAPnGO for cruising and flying. I've had mine for 4 years and I've used it all over the USA, the Caribbean and Europe. This three-wheel scooter maneuvers easily on ships and has a battery range of 15 miles. When flying you can ride the scooter right down the jetway, take off the lithium ion battery (3 lbs.) and carry it on the plane. The scooter will be placed in cargo and delivered to your destination jetway, where you just reattach the battery and go on your way.
The latest model 335 is available on Amazon @ $1,299 (same price as on Glion's site). The scooter frame with battery weighs just 31 lbs. and the current seat weighs 15 lbs. (my older one is 20 lbs.). It's easy for this senior lady to load the two pieces into the trunk of my Corolla.
I usually get an accessible cabin, but if I don't I can drive this 22" wide scooter through the cabin doors of all but the very oldest ships (those were on Holland America, when I had to take it apart and lift it sideways through the door). If I don't have an accessible cabin with an automatic door, using a doorstop to prop the door open makes it much easier.