Tammy you ask a great question and the answer must include what works best for you and your team. I was a CRNA, Nurse Anesthetist, for 33 years and administered thousands of general, spinal and epidermal anesthetics. Your safety is primary and the skill of your team should be directed toward your success and comfortable course. I tend to recommend a spinal with long acting components (a mix of local anesthetic and narcotic) that can keep you comfortable during surgery and post operatively for many hours. Usually sedation with a spinal is very effective in helping people feel anywhere from relaxed to completely asleep. Your anesthetist will be with you at all times during the surgery. Technically a bit more tricky, a continuous epidural can be titrated (delivered through a tiny catheter) for what you and the surgeon need for surgery and for days post operatively. Doesn't sound like they offer that option however.
A spinal is typically "placed" (a very careful needle shot) while you are curled up and have some sedation. Your ability to get in good position for the procedure is helpful and you are correct in assuming that back injuries could make this option more difficult or even contraindicated for you. Your team will want to know about your complete medical history and are required to give you informed consent, describing the procedure and potential risks. I advise your cooperation and going in with a positive attitude, knowing you will recover and have so much to look forward to. This is considered by many staff as a "quality of life operation" vs. the pathology of removing cancer or disease.
There are particular risks such as a a post dural puncture headache from a spinal or epidural. General anesthesia involves multiple medications to get you to sleep, relax your muscles and keep you there and are typically a combination of intravenous drugs and inhaled gases. Anesthesia for that length of time involves manipulation of a patient's airway (laryngeal mask or endotracheal tube) and breathing and, of course, consciousness. Sedation and complete amnesia are two different things and you could ask your anesthetist to explain what you should expect. Most peer reviewed studies indicate that overall relative risks and recovery are similar while your good health and the anesthetist's skill and vigilance are pluses for you.
Either way you will be in a recovery room area after surgery where you will become more wake and may feel thirsty and hungry but please don't expect real food until hours later. Time may feel like it "stood still" for the whole day.
I am excited for you and honestly think you will do very well. Dr. Brassard and the team have likely established a very good "routine" and mucho experience. Happy landings!