We really enjoyed our stay at Isabel's apartment. Unbeatable location in the middle of Alfama, with a private patio. Quiet and comfy, and with heating for the colder months.
Isabel was flexible and very responsive, and instantly let us know when we had forgotten something when we left :).
Tea drinkers: You'll find a kettle in the kitchen.
Remote workers: Wifi is reliable and fast enough.
Coffee drinkers: Antu serves V60.
As others have noted, don't bump your head upstairs, and you'll have a great time.