just do something that you know you would enjoy. Considering you will be studying part time for 5 years plus, you don't want it to be a bore or a bind in a few years time. As for professional quaifications, most degrees just show you have the ability to study and are a record of attainment. Just how many lawyers have graduate law degrees - not many by my reckoning.
The degrees available in aviation management tend to be post grad qualifications and in my experience will probably disqualify you for an airline management post! (Read into that what you will!) They are like industry specific MBAs and there's a bit of a backlash against those type of qualifications at the moment.
Personally, I would do History and avoid like the plague something like accountancy. Having to get an already deferred assignment done on a topic such as stock control on depressing nightstop in a gloomy hotel may make you a suicide statistic!
As for ground posts - flying bores the bum off me now. I quite enjoy my 4 days in the office a month!