How about just going into the City, see the port and the Raddison Fort George area itself.
Almost everything is in walking distance but the taxi is almost dirt cheap for 4 people. Most of your taxi drivers will enlighten you on sights as you drive past or will be glad to take you to anything in a good area. They will not be out to try to frighten the living day lights out of you.
In the city, driving is not fast but sometimes a tad frightening since you want to be the driver and the scenic viewer as well
There is so much to be seen and your time is limited, I agree.
Everyone says to avoid the city, they don't know what they are missing if they don't try to experience some of the wonders of the country. It's not all about the waters and sunshine.
I liked the ZOO, and I am not a zoo person. I think the animals and the habitat they have are totally different than the Americanized Zoo's.
It's a wonderful place to view animals and NOT know what they are, we know most of the animals in the US, or proclaim to. These animals are in a good place.
Ask your resort for information, ask your travel agent, if they have actually been to Belize or ask at the Airport in Belize. There is good information and most of the people of the country are very open to show and tell you about their land. So dislike ourselves in the US.
The internet offers so much, see what you can seek and hopefully you will find something that suits all of you.
Again, one day will not be enough to do several things unless you don't mind flying back to AC.
Another thought. If you want to see a smaller town and view some of the true natives, go to Placencia by air, if $$ allows. Go to Hopkins via Dangriga and then taxi. There are many options. There is a bus as well for tighter purse strings. Time is a factor.
OR Placencia...the list goes on and on.
Have fun and enjoy whatever you do, it's a country of many choices