Yeah, about time people are giving Dominica its props. If you book a Trafalgar Falls tour on your own. it will be inexpensive and fun... And bring some clothing you can get soaked because there is a fantastic hot springs there. If you're more adventurous, definately the kayak/snorkel adventure (but you have some cost involved). Whatever you do- don't stay at port in Dominica; there is really nothing to do.
**St. Thomas** it'll cost you some, but you can book your on way to St John. Cab to Red Hook Ferry. Ferry cost to St. John. Cab from the ferry to a beach in St. John. And then all that back.
**Aruba** we went to Palm Beach. You just have to pay for the cab ride. The beaches are public, so you can go wheverever you want pretty much. You could rent an umbrella and chair and such.
**Barbados** the Boatyard is great. It's a bar on the beach. And it really heats up at night, if you like a party atmosphere (mostly young adults drinking til their silly). You can walk there, but it was a little creepy for us (vendors, drug offers, people asking for money, etc) - take a cab if you can afford it. Maybe $10 or so.
Hope this helps.