I would concur with the 8" dob if you can save up for one.
For sitting, you can build a chair on the cheap called the denver chair or similar.
http://www.budgetastronomer.ca/index...bserving-chair
Just been out using the SW Heritage 130 and I will really need to sort out the stability issue and a seating arrangement. I'm currently having to bend over a bit too much because the table is a little low but not so low as to allow me to sit down. Still, happy with my purchase but it's something you should consider.
Also consider that you will want to add to the eyepieces of any telescope you end up purchasing. The ones with the Aldi dob won't cut it I'm afraid but the best advise is to use the ones you get with the scope and see what objects take your fancy, this will help decide on which eyepieces to go for.
Good luck.