Hi!
The best rooms in Caribbean Beach, view wise, are locate din the Aruba village. You will ahve the early morning sunrise and be on the quieter side of the lake, yet only a short 4-7 mins walk to Old Port Royale. For great unobstructed lake views (b/c a lot of "lake views" merely just face the lake, but are covered by the abundant foliage) request a room in Aruba 5256--5261. They are also on the second floor, which is really nice. Both rooms 5256 and 5257 are corner rooms, over looking the lake and practicaly the quiet pool. These rooms are a MUST for us each vacation.
You mention a first choice being Aruba 51. I don't know if this will hinder your plans, but Aruba 51 is designated as a smoking building. But if you are a smoker or want to risk getting a "not too bad of a smoky room", Aruba 5152--5154 offers great second floor unobstructed views of the lake (we know this b/c Aruba 5153 was our first ever room on Disney property, we fell in love, but then they turned it into a smoking building).
As for Jamaica, there are not as many direct views of the lake, but more of sideways views over looking courtyards and then trees and then lake. But still, many nice views are possible.
I hope I was able to offer some help. Definately try for Aruba if you can, it's great there. Illuminations can also be seen for the most part from the Aruba bus stop, which is practically right across the street from Epcot.
Oh, and also, if you are in Aruba, the lowered numbered buildings are a little bit more of a walk to the Aruba bus stop, which for some reason is located behind Aruba 56, the last building of the complex, and is confusing to get to But dont worry. The short, organized way (if you are in 51--53 buildings) is to head to the quiet pool and take the entrance closest on the far side from you (actually walk around the pool) and follow that "main" path directly to the bus stop. It spits you out around Aruba 55. Couldn't be easier (but I know as kids we got lost a lot).
Enjoy the Aruba beach as well, and just the allure of the colorful retreat. I wish I was going there soon too!
Oh, and also (LOL) those Aruba 52 room numbers I gave you really are good. CBR has postcards that are actual photgraphs and the photo that they use (which I am looking at now as I type in my college dorm) is at Aruba 5256--5261. That wing of rooms is how they are selling and advertising their beautiful Resort. Hope I was of assistance and that everything goes well.
Enjoy your trip, sorry for rambling too.
Donnie