From my experience, scooter tend to require maintenance more often than motorcycles and getting to things are complicated due to all the plastic. However, this varies from scooter to scooter as well as motorcycle to motorcycle.
Valve adjustments in particular can be very complicated on a scooter due to all the body work. Adjusting the valves on my KLR is easier than on my Sport City 250. This, despite the fact that the Sport City has Screw & Locknut adjusters and the KLR uses shims. Luckily, neither requires valve adjustments that often. On my Kymco on the other hand, Valve adjustments are very easy, but are required every 2500 miles. I have read that the valve adjustment on the Burgman 400 is very time consuming so you may want to look into that.
I ride, Therefore I Am.