ST Thomas/St John accommodations

Hello,

I am going to St thomas for a conference at the end of October and I'm staying at the Frenchman's Reef for 2 nights and then I'm staying for an extra two nights after that so I have a few questions:

1. Should I continue to stay at the Frenchman's Reef? Is the beach there swimmable? Is it as dirty and rude as people say?
2. Should I spend the additional time on St John? Is there a good budget place to stay there?
3. If I stay on St Thomas where is the best semi-budget place to stay? And which beach is the nicest?

I really just want a clean place to stay that's in close walking distance to a nice calm beach away from any cruise ships... and my budget is $200 and under.

Any advice would be greatly appreciated. Thanks!