I have been using Activa 3G for around an year and I am very much happy with its performance.
I am getting the mileage of 58Kms per 1 litre petrol. Some of my friends have purchased other Scotties like Maestero and Jupiter are not at all happy since they are not even getting mileage of 50 Kms per litre.
In addition to its mileage, its pick up has been good and there were no repairs till now.
I would always go with economy speed 40-50 kmph and I would suggest the same for every one to get top mileage.
Though Active 3G is priced a bit high compared to other available Scotties, I would suggest you to go with Activa 3G only.
Now the new model has come which is Activa 4G which my brother has purchased recently and hard that the performance of it also has been similar as Activa 3G.
2 people can easily ride on this bike and even if there are 3 people also, its performance has been good where as other brand bikes will not perform in the same way and lead to repairs.