The naples pier is free, beach is free and youll see dolphins near sunset time...its lovely, take a picnic basket, a ball and relax and watch the show..parking is a fee, it takes charge cards or coins
The naples zoo is good for a few hours...pick up one of those area booklets at the supermarket etc..,..coupons for a few dollars off

The boat ride is nice (included) feeding giraffes is $5 but instead, you can just watch and be just as close, so save the money...
Publix has great picnic type lunches ready packed or made to order.
Not sure where youll be but there all over..
For a good meal that isnot expensive, consider Mels diner...YUM food and Options galore..
There is tin city, kitschy shops, overpriced, but you can walk around a bit, the trolley is also there...also coupon..fun to see the area
Laudermilk Beach/Park is great...you again pay to park, do yourself a favor and use a charge instead of the coins...there is a Beautiful beach, washroom and outside showers, area to eat, covered palapas to use (they are to the right side of beach, which is not huge by the way) a nice short walk to the water..There is also a concession stand.
You wan walk fifth avenue and third street...which s loaded with little shops (some pricey) but there is also a great ice cream shop that smells so good with the fresh made cones...youll see the lines LOL
There is also a really fun store if you have a girl (and for any woman) which is so fun and inexpensive overall, its called best of everything...you get a jewelry tray and you walk up and down these rows and rows of fun, mostly summer type jewelry, watches barettes, etc etc...I am talking like $3, 5, 10 dollars...the place is always packed lol...
anyhoo, fun to just see it if you are downtown,
Park on the street OR park for free behind Tommy Bahamas...It literally is like a 5 square mile area of wonderful shops, small bistros etc...(they are costly mostly)
Lovely at night when the lights are twinkling...check out tripadvisor for the naples area...
We LOVE Naples..........bet you can tell......