If you're looking for somewhere exotic my wife and I just got back from St. Vincent and the Grenadines. The entire area is jaw dropping beauty. The conditions were perfect, the tradewinds blow 20-30 from the east for the entire dry season. The company we booked with is also excellent. Barefoot Offshore Sailing School out of St. Vincent.
My wife and I just did the same. We got our 101/103/104/114 through Barefoot Offshore.
Getting to St. Vincent and the Grenadines is an adventure in itself unless you're Canadian. We flew into St. Lucia on Delta and then used SVG Air to get to St. Vincent. SVG Air uses small twin-prop planes that are sort of a shuttle. St. Lucia to St. Vincent isn't a direct flight and depending on where people need to go that day, you may end up landing on 3 other islands (Bequia, Union, Canouan) before getting to St. Vincent. That was the case for us. On the way back to St. Lucia, we only stopped at one other island (Mustique). Lots of interesting landings and take-offs!
Let's not kid ourselves, if you don't have a lot of sailing experience, doing 101/103/104 and maybe 114 also in a week is a lot. It's a ton of information to learn and skills to master in a week's time. We got it done, but were pretty mentally and physically exhausted at the end of the trip. That said, it was an amazing feeling of accomplishment.
The conditions in St. Vincent and the Grenadines were challenging as well, which pushed us along a bit quicker as well. Days of 25 kts winds and 8-10 ft seas gave us some good experience. Our last day was a beat in 30 kts and 11-13 ft seas and it was a blast!
Is a week of training going to make you a competent sailor? No way! But, it's a good way to jumpstart your knowledge and get you some great experience. Take a look at what it would cost to rent a sailboat for 7 days and then compare that to the experience of living on a sailboat for a week and it's a pretty good value.
Edit: I realized I didn't do a very good job of answering your questions.
- I'm not super familiar with RYA so I can't answer if RYA will accept your 101. I do know that RYA is viewed by many as superior to ASA and that RYA gives you a path to an ICC which is required for many spots in the Med.
- As far as whether you can go from a 101 and some sailing experience to doing your 103/104? In my case it was yes. I did 101/103/104/114 on the same trip with very little prior sailing experience. If you and your wife both have some experience under your belt, it shouldn't be too difficult for you. The written tests aren't difficult if you study. I got a 100 on my 101, a 97 on my 103 a 95 on my 104 and a 98 on the 114. The on the water practical skills are what seem to trip up some people. You need a good "wind sense" and the ability to go from one point of sail to another and be able to tell others what they need to do to help get there. One of the skills you'll do is a 360 degree turn going through all points of sail with a pause at each point to ensure proper trim and a steady course.