If you aren't feeling the vibes in downtown Perth, the only other place you have to go that has a decent number of business establishments is to the ocean. Catering to a more artsy sect than greater Perth, you'll find this to be a cool area to hang out a half hour ride from the city.
Albeit a tad bit overpriced (par for Perth), Fremantle has a good variety of restaurants and drinking establishments in close proximity to the water, with the majority of both existing on or near South Terrace. There's a great range of food (Thai, Italian, sandwiches, ice cream, etc.) to be found here and a handful of classic pubs. Head across the esplanade to Fisherman's Wharf if you'd like the area's best seafood and a few drinks at the excellent Little Creatures Brewery. Also, a great place for tunes, drinks, and food during the day is Clancy's Fish Pub on Cantonment.