I would also recommend a car, as Lisbon it about an hour's drive away and the resort is quite remote, even Obidos being a 15-minute trip away. I had stupidly left my driving licence at home, so we ended up spending a fortune on taxis. That said, the drivers were all lovely, and offer reasonably priced day-tours to various places of interest. (And, yes, the surroundings are gorgeous!!) If you like, I'll check whether have the email address of our favourite English-speaking driver.
As for the resort, we thoroughly enjoyed our stay - that pool is a marvel - but again having no car, we purchased everyday items like sanitary pads and contact lens solution from the hotel convenience store and believe me, it was daylight robbery. Still, I only had myself to blame for my scatter-brainedness!