If it were me, I'd stay in Ubud and do a late check-out or even book an extra day. While the ride to the airport will be longer (45 minutes?), you really have all day to get there so there's not much point in moving. I hope you are hiring a driver (such as Putu, so often mentioned on this forum) so that you can get outside of Ubud for day trips - there's plenty to see and do in your 5 days.

Good experience at Hyatt Sanur beautiful great beach

booking.com otel.com bettterbidding.com

nice beach hotel makes more logistical sense

so I might head there.

Have fun!

thank you both very much. although both different opinions, i am still confused

I don't think it makes sense to move to a different place for your last full day. Relax and enjoy your stay in Ubud. As you point out, your plane leaves late so there is no reason to stress about getting to the airport.

I would stay in Ubud. There is loads to do, bike rides, hiking through the rice terraces, rafting etc. Far better IMHO than just hanging out at a big hotel. Definitely organise a driver as craig suggests as you will get so much more out of your time there.

I was also just in Ubud and I would stay in Ubud. The Hyatt though nice is huge and if you are assigned a room in their third building it is 1/4 or so it seems just to the lobby.
If your budget allows and there is availability which is problematic we just stayed at one of the most elegant hotels in our 40+ years of travel-The Chedi Club. We stayed in a 1 bedroom suite that may not permit 3 people but it one-ups the Four Seasons-sayan in our opinion. It was $320/night with taxes and included breakfast.
Keep in mind the trip from Ubud or almost anywhere other than right near the airport, which is not that nice, except for Jimbaran Bay will take 75-90 minutes even in mid-day traffic.
Though they ask you to arrive 3 hrs. before for international in our travels through Denpensar 2 hours prior to departure time is sufficient, in my opinion.

I think it depends on what your son likes to do. If he's a swimming/surfing kid then only the ocean will do. If he likes outdoorsy/nature-y activities or is interested in art/architecture/theater then he'll easily fill up 5 days/nights in the Ubud area.

We spent a lot of time in Bali when my son was a teenager. He fell into all of the above interest categories, but the big wave beach at Seminyak was and is still his favorite. 18 is tough on your own, because it's too young for the bars and clubs and too old to hang out with your parents 24/7.

I’m not exactly sure where Nefatari is located but it appears to be in the countryside outside of Ubud and may be on the too quiet side for a teenager. You might try to set up some activities that he can do on his own, while you and your spouse are relaxing around the villa.

There are tons of treks, hikes, climbs, bikerides that can be arranged in the area. If he likes adventure sports, he could climb one of the mountains predawn, go north or east for snorkeling/scuba, explore a cave. If he likes the arts there are plenty of hands-on classes – batik, woodcarving, painting – and there are performances all over the area every night.

You might take a look at the new W. It’s a little over the top for my taste, but I think that a teenager would find it lively, especially post Ubud. Other than Jimbaran, all of the south Bali beaches are about the same distance/time from the airport.

thank you very much for all your replies.
it gives me something to think about.
Marmot - you have given me a better suggestion than Jimbaran. I will look at the W as I think it would be fun to be there for a night.
My son sounds like yours, and I think he would like a bit of everything.
I have already planned the bike ride, as I think it would interest us all.
I am quite interested in a snorkeling trip, and a wondering where we could go from Ubud? Would Amed be too far for a day trip?

For snorkeling, while you are in Seminyak it would be easy and fast to just take one of the trips to Nusa Lembongan/Nusa Penida. They are much more set up for things like banana boating and activities that would interest a teenager. Plus they have excellent snorkeling and people even surf there.

Amed is pretty laid back and quiet. If you want quiet you could even go to Pemuteran and take a boat to Menjangan but you really should budget at least an overnight if not 2 nights for that, as there are so many sights to see on the way over the mountains.

Nusa Lembongan and Penida I would rate a 2 with 5 being the best in quality snorkeling if your son has snorkeled in several other places such as Caribbean, i.e. Bonaire, Grand Cayman or Belize or in Cozemal or in Thailand, etc. I was there a few years ago and with some coral bleaching since around it cabnnot be better unfortunately. I did see a number of surfers though the waves were not high the day I was there. You have to go all around the island a 2.5 hour drive from Seminyak to catch a fast ferry to an island, whose name escaoes me, that several acquaintencies said was quite good bit still not anywhere near Sunaken a 40 minute flight to Monado and snorkeling that is 4.5 out of 5.\ in my opinion.