National - need help making a reservation at HNL

I am trying to make a reservation at HNL for 7 days.3/15~3/22
I have 2 free days, 2 "ONE TWO FREE" , and I will pay for 3 days using coupon code NF5572ZDF which comes out $135.
My question is if i use 3/15 freeday, and 3/16~19 pay, and 19~22 free day do i have to return the car and rent it again? how does it work? this is the first time using free day for me.
Also I will be staying at Hyatt regency waikiki for 7 days, should i just rent 4 days instead of 7 days? Any advise? first time visiting HNL.

I am trying to make a reservation at HNL for 7 days.3/15~3/22
I have 2 free days, 2 "ONE TWO FREE" , and I will pay for 3 days using coupon code NF5572ZDF which comes out $135.
My question is if i use 3/15 freeday, and 3/16~19 pay, and 19~22 free day do i have to return the car and rent it again? how does it work? this is the first time using free day for me.
Also I will be staying at Hyatt regency waikiki for 7 days, should i just rent 4 days instead of 7 days? Any advise? first time visiting HNL.

To do as you posted (in order to stack the coupons), you'll have to plan on having to return 2x to change contracts (and possibly cars), with luck you'll be able to phone in to close the "old" contract and "open" the new one - YMMV on this issue.

As you probably know from the Hyatt forum, Valet parking at the HNL HR is about $30 a day (self parking is not recommended in their garage), alternate places run about $10 a day. Whether you'll need a car depends on what you are planning on doing, if you are staying only in Waikiki, you don't need a car but if you're going away from Waikiki, a car is a good idea. If you don't rent for the whole time, look into renting at the Ala Moana location and returning at the airport (or vice versa).

I'll second this. Parking down in Waikiki is expensive and/or a huge pain (depending on exactly how expensive you make it), and you're only about 0.75 miles away from National's Waikiki location. If you can get away with renting from down there for only part of your trip, then I highly recommend it.

If you're staying down in Waikiki for any of the days, then you definitely don't need a car those days. You can cab it to the nearer parts of Honolulu, round trip, for not much more than you'd be paying just to park. Honolulu can also be confusing to drive around since it's not really built on a grid and has some awkward sets of one-way streets.

The bus system is OK, but not highly efficient, so I wouldn't waste vacation time on it unless I was sure I'd be staying on high-frequency routes. For going outside Honolulu (so past Pearl Harbor in the east or Diamond Head in the west, or over the mountains), you'll definitely want a car.

The only downside is that the Waikiki location is only open 7 AM to 7 PM, and doesn't have after-hours drops - they'll tow the car if you leave it there. As such, you're kind of forced into renting in the morning and dropping the next morning, unless you really want it just for a day trip where you're sure you'll be back by 7.

Also, last time I was in the Waikiki location, I'm pretty sure I saw a tourist couple in front of me getting charged a drop fee for dropping it at the airport. It was pretty modest, though. I forget the number, but I remember thinking that it was less than you'd pay for a cab from Waikiki to the airport. If you time your rental right, this might work well with a redeye back to the mainland.

I rented from HNL for about 46 days last summer and they had to split it into two contracts, and made me come back to sign, but they were super nice and let me switch out cars when I came back. So you still might have to go back and resign a new contract but you might be able to get a better car out of the deal. The manager of the location is fantastic!!! She's extremely nice and gives great food recommendations. I'll look for her card and try to post her contact info if i find it.
Enjoy HNL and if you like burgers, check out "Burgers on the Edge" and you've got to hit Leonard's for some Malasadas!