We (party of 5 boys) have selected Cristina her appartment based on the location (bario alto). This area has a vivid nightlife and is centrally positioned in Lisabon. The appartment is very nice and all the bedrooms are positioned in the back. This ensures a great and quiet sleep.
You can basically walk from here to all relevant sites.
Finally I like to underline that Cristina is a great host. We were welcomed with food and drinks and during our stay it was easy to get in touch. 100% recommended!