I'll tell you the best, but I'll also tell you the WORST character to bring:

• Zoo
Best: Summer (Rachel's environmentalist friend). Has a great deal of knowledge and would tell you interesting conservation facts.
Worst: Summer (if the Zoo is bad). Would be furiously complaining the entire time. Just absolutely seething for the entire day.

• Concert
Best: Dinky. Impeccable concert vibes. Could give you upsies for a better view.
Worst: Tallica. Absolute music snob. Would kill the whole vibe.

• Food Festival
Best: Lily Thorne. She's a baker and she'd probably have her own stall there. Would treat you to all the best food at the venue.
Worst: Jam. A kleptomaniac who can almost immediately dissolve food. Bad idea.

• Theme Park
Best: Rachel. She'd say yes to every ride. Try and win every stuffed toy. You could make out on the ferris wheel. A perfect day.
Worst: Connie - too short for the rides.