The vast majority of the world has legal or decriminalized sex work. The US is actually in the minority when it comes to the full criminalization of sex work. I would advise to center your trip around several locations you really want to travel to and also your budget. Once you have those figured out then I would say to start your search in regards to setting up appointments with providers. Red light districts are going to be seedy anywhere you go, so if that is what you prefer for finding a companion please be aware of this!

Toronto is fine

Went there and hated it.

It seems like the waters are a bit muddled with various regulations which you could look into, but it’s my understanding that SW is decriminalized in Australia. I’ve always wanted to go there anyways. I know a lot of people who say they loved it there. Especially US Navy guys. Not only, but especially.  

You are better off here in the United States

I did just watch several You tube videos of the red light districts in both. Portugal from the videos looks much nicer. Prices look to be 60 to 100 euros, in both areas,  or $66 to $111 US. I am assuming with those prices you are going to either have to spring for the hotel or you will be getting a car date.  
Both look to also have Asian massage parlors averaging 40 euros, or $44.50.  
As always, your results may vary.  Be careful and be safe!

Why would anyone not want to try something new, especially where it's legal and less expensive than the US?
You are giving bad advice because you're greedy.

Try Aruba!

Kokomo?

I love Aruba.  Wife and I bought a timeshare there years ago,  usually go once a year.   The red light district is in town of San Nicolas @ the southern end of the island.  I’ve never been,  but met a couple of guys on the plane that liked it so much,  they bought one of the bars where you meet the girls.   My understanding that most of the working girls there are from Columbia and Venezuela.  Looks kinda seedy,  but it is safe. Aruba government takes that seriously.  It is a tourist destination and the Natalie Holloway thing years ago damn near destroyed the economy.

There is only one place that is fantastic on Curacao, the Boase resort.

island for business and pleasure during the 80's and 90's.  Business because they had no tax treaty with the U.S., and you could conduct business and maintain bank accounts in any major currency.  Pleasure because this was before Venezuela went socialist, so many of the top Venezuelan escorts would come there to work for a month at a time.  

I was in Aruba for 7-nights in 2018 before the pandemic and had tons of fun. We stayed in town (Orenjestad) at a nice hotel but traveled to San Nicholas on two nights. It’s about a 20-minute taxi ride. The first night we went early like 8pm and were back in town by midnight. We scouted and scored and cheered our success. The second trip was much better but more risk. We got there about 10pm and got drunk. But, thankfully, we hired and retained a great taxi driver who stayed with us all night and got us out of at least one awkward situation. You don’t want to goto San Nicholas late and drunk and without a taxi or ride home.