Staff Technician at Steward Observatory so I have quite a bit of experience.
Tell me what your long term plans might be.  For instance, do you want to stay with strictly observing?  Or do you plan on moving on to imaging (astrophotography)?  You can get by with a smaller telescope for imaging but you will need a special mount that will guide automatically.  If you are going to stay with visual observing I would recommend not less than a 10" Dobsonian telescope.  Look at it this way, with a visual scope you will see an image comprised of one frame.  With astrophotography you can shoot unlimited frames that can be combined so you can use a smaller telescope.  This is a tough decision because if you buy something that do not satisfy you it may spell the end of your hobby instead of the beginning.  Let me know, if you like, exactly what you are planning and I will adivse you as best as I can.  I am a retired Sr. Staff Technician at Steward Observatory so I have quite a bit of experience.  I live in Tucson, AZ.