Hi Jennifer, and welcome-
* What would make you book my Hotel as opposed to another Hotel with a Towers concept in the same city (ofcourse)?
I would definitely book your Towers if I had elite status with only Sheraton for the upgrade to Tower. If I was (and I am a Hilton Gold+ and Marriott Plat) and had no status with Sheraton I would not even look at the Sheraton unless there was a conference there in which I was attending. Additionally , all things being equal, I would stay there if good reviews were posted here, flyertalk, in the Sheraton forum. Also if there was a mileage or price special, I would look there 1st. Finally if your hotel was the only place to which I had easy access to my reason for being in Lisbon.
* What services represent to you value for money? What do you feel justifies the premium one has to pay for a Tower room?
Services related to making the guest feel special. Again, seen in elite status situations such as a bottle of wine in the room, calling the room after we check in making sure all was well. Concierge floor situations, such as the cocktail lounge, free breakfast, access to tough to find goings on around town. Things related to 4-5* concierge services.
* What additional services would you expect from a Tower concept.
See above. Mileage and/or package specials. Spa type services and discounts as well.
* What would make you say "WOW" I shall be back again?
Quality of the bed, quality of the room, quality of the breakfast and cocktail lounge (on the Tower floor). Easy checkout. Service and quality items. I have stayed 42 weeks in a row at the same hotel due to a great price, excellent service, and a great staff (remembering my name after 2nd day, asking how family was, offering to include in various situations that made me feel as if I had an extended family). Not expensive items, just extra effort, and good product related things that we may consider the norm. Down pillows, a call once per stay to offer any extra service, tips on the city, etc...(and obviously good housekeeping staff, standard service things that can never slip) I'm sure others can more creative but this is my list of items. Good luck!
* What additional recognition do you expect as a Starwood Preferred guest?