We've been twice, both times were via Cruise Ships, and late in the year. These were not big, fancy ships, just average Joe UK ones.
Dominica is a beautiful, lush, green, uncommercialised island that the locals should be very proud of. The locals themselves are very friendly and polite.
On our first visit we braved the enslaught of taxi drivers that rush to greet Cruise passengers. You just say where you want to visit and they tell you their price. We got together a small minivan (approx 10 passengers) to go to the Falls.
Our taxi driver was a young man who rented the vehicle. He took us up the very windy roads, stopping frequently to either point out things like pineapples growing by the roadside or local houses to explain their way of life or at a roadside shack so we could buy a cool drink. He spoke to us all the time and answered our questions happily. There were many other vehicles on the roads going to the same place, especially when ships were docked, but the taxi drivers seem to know how to work their route so you don't all arrive at the same place at the same time.
The climb up to the falls can be steep in places, slippy when wet and very crowded. There were locals asking if you wanted to venture further in, to other falls, or if they could help by taking your photograph etc (all at a price)
We did visit somewhere else, but it was a few years ago and I can't recall all the details at the moment!
On our most recent visit, again via cruise Ship, we had our two kids with us. We first had a look around the little market at the back of the museum. The prices here are very reasonable. main buys were bead jewelery, T-shirts, wooden carvings, hair braiding, baskets. Things for kids and adults alike (we found it hard for the kids to buy trinkets on some of the islands we visited).
Then we walked up to the Botanical gardens. It's basically a park, with an aviary but the locals love it and it was full of local school kids. One lot were having their Sports Day. There was a tree at the bottom of a set of steps and it was alive with different birds. The noise was incredible and you could see tiny hummingbirds flitting about
Later that day we went on a Whale Watching Tour. Now we're not talking Moby Dick here, but Sperm Whales. They're larger than Dolphins and looked black in colour. The catamarran we went out on was very modern and clean and it was lovely zooping along. They periodically stop so they can listen for the whales. The crew were experts at spotting a Water Spout on the horizon and would zip off again as this meant a whale was surfacing. They don't get too close, but close enough and it was awesome to see these creatures. We only saw two small groups, but it's all down to pure luck.
Would we go again? definitely.
Weather - VERY hot.