Yes, if possible, arrive as early as possible, and use the single rider lines.
As far as just enjoying the parks, here are some non-attraction activities.
1. Photo opps in Toon Lagoon.
- There are so many great Easter eggs and fun details to take in in this area that most people just walk right past.
- Take time to explore the outsides of the buildings in this area. Lots of fun places to pose for pictures.
- Check out the board walk area with all the campy jokes and silly puns.
2. Take a Look at the Playground Areas
- If I Ran the Zoo in Dr Seuss Area - This is a fun area to walk through even if you don't have little kids. There are lots of fun details and hands-on-exhibits to take in here.
- Go up to the back side of Me Ship the Olive in Toon Lagoon, and there are free water guns you can fire on riders as they float past on the raft ride (assuming the raft ride is running and not on refurb right now, not sure).
- Camp Jurassic - Go to the back of the area and take a walk through the caves. Worth at least a quick look.
3. Find your family crest at the little store in the Lost Continent.
4. People watch at the Fountain in the Lost Continent.
- This is such a fun entertaining activity, but don't get too close unless you want to get wet. It's not always on, so sometimes you have to check back a few times before you catch him interacting with people. You can talk to him and ask him questions.
5. Google some Easter Eggs before you go and look for them around the park.
- The love birds at port of entry in Island of Adventure.
- The Mythos troll.
- References to old movies and attractions like Jaws.
- The phone booths.
- Listen at doors, try handles, look in windows, look up at ceilings, etc.
- The Berlin Wall behind Hard Rock.
- Really look around the Seuss area. Find Horton's eggs. See what happens when you throw a coin in the fish's mouth in the pond. Look around inside the circus tent. Take a stroll through the Truffula trees and listen at the yellow "pipes". Lot's of great opportunities in this land to really just stroll around and take in little details.
- There are tons and tons more than the above. Have fun exploring.
6. Check out the different bakeries
- most of have fun themed cookies, cupcakes, and other desserts that are worth a look
- have a treat
7. Have a fun themed meal
- quick service at one of the HP restaurants
- nice sit down at Mythos
- character theming at Toothsome, going just for an elaborate desert is always fun
8. Really explore all that the HP areas have to offer, not just the rides
- Exchange your muggle money for wizarding
- find moaning Myrtle
- find the talking mirror
- perform spells / find the secret spell spots
- explore Knockturn Alley
- send mail by owl post
- watch the wand show
- look up at ceilings when in buildings, great details all around
- listen at doors, look in windows
- great photo opp in front of window down back alley off side of Three Broomsticks
- find Kreature
- call the ministry
- watch the stage shows and Castle projection show (if running)
9. Meet and greets with characters
10. Watch the parade in Universal Studios
11. Check out a baby dinosaur hatching at the Discovery Center
12. Watch a Pilot at the NBC Media Center and get paid for it
13. Watch the 3 different stage shows at Universal Studios
14. Watch all the different street performers at Universal Studios