The Hard Rock Cafe in LA is located at base of the Beverly Center mall at the corner of Beverly Blvd & San Vicente.
To get to the the Universal HRC, you can take Beverly Blvd east to Fairfax . Turn left on Fairfax and then head north to Hollywood Blvd. Make a right on Hollywood and head east to Highland . From here, you have a few options.
Option#1--Park at the Hollywood & Highland Shopping complex and then take the subway north to the Universal Station. From there, you will emerge and then cross the street to a shuttle stop that will take you up to Universal Studios. You will be let off at the City Walk area of the park. Once you're in City Walk make sure you go right and it will take you to HRC. If you go left, it will lead you to the theme park.
Option#2--Turn left on Highland Ave and head north. From here you have 2 more options.
Option A--If you stay to the the right lanes, the steet will lead you to the North 101 fwy on ramp (this is an interesting on ramp since it will take you to the far left lane of the Fwy aka the fast lane). So once you're on the freeway, try to make your way to the far right lanes asap since you will need to exit the Lankershim Blvd off ramp only abou 3/4 miles away. Once you exit, turn right and then immediately turn right again. This will take you up the hill to parking.
Option B--If you stay to the left lanes, Highland will become Cahuenga blvd. Just keep going north on Cahuenga. You will need to make a right turn that takes you up Universal & Citywalk (don't recall the name of the street, but they have tons of signs there so you should be fine)
I think Option 2 will be the fastest route for you since you don't need to look for parking at H&H and wait for the subway and then have to wait for the shuttle. As far as Option A or B, its really a toss up. Sometimes the both Cahuenga and the 101 fwy are jammed, sometimes one is jammed and one isn't.
