Barcelona and Sitges

Hi all- have my big 4-0 bday coming up end of june/early july and I've got a small group of about 8 friends joining me in Barcelona for 5 days and Sitges for 4 days - I would love any and all recommendations for off the beaten path things to see/do- esp interesting shops and food spots. Obviously all the big tourist spots are well known, have tons of websites/resources about them but I am really after the random spots you find after wandering a city for a while or befriending locals. This is a mix of gays (guys), straights (guys and girls) so dont need it all to be lgbt. Thanks so much